AT Command Set and Register Summary for

Cisco PVDM2 Digital Modems

First Published: August 15, 2007

Last Updated: December 5, 2007

This document describes modem AT commands and S-registers for Cisco PVDM2-xxDM digital
modems.

Note IOS feature support for PVDM2-xxDM digital modems supersedes CSM V12 capabilities. Please refer
to the IOS feature set documentation for details of support on specific platforms.

For information about managing modems on Cisco access gateways using Cisco IOS software
commands, refer to the software configuration guide for the access server in which the modems are
installed.
This document contains the following sections:
• Obtaining Documentation, Obtaining Support, and Security Guidelines, page 2
• Entering AT Commands, page 2
• Command Syntax, page 4
• AT Command Set Summary, page 5
• AT Commands Description, page 11
• V92 Data Mode AT Commands, page 55
• Error Detection and Data Compression Commands, page 64
• MNP 10EC Commands, page 66
• AT Command Result Codes, page 67
• S Registers, page 74
• FAX Class 2 Commands, page 96

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© 2007 Cisco Systems, Inc. All rights reserved.
 Obtaining Documentation, Obtaining Support, and Security Guidelines

Obtaining Documentation, Obtaining Support, and Security

Guidelines
For information on obtaining documentation, obtaining support, providing documentation feedback,
security guidelines, and also recommended aliases and general Cisco documents, see the monthly
What’s New in Cisco Product Documentation, which also lists all new and revised Cisco technical
documentation, at:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html

Entering AT Commands
To send AT commands to the modem, you must first put the modem in AT command mode. Entering AT
command mode involves a reverse Telnet procedure. The table below shows how to enter AT command
mode from Cisco IOS EXEC mode using reverse Telnet.
.

Step Command Purpose

Step 1 > telnet ip-address line# Open a reverse Telnet connection to the modem. In this
example, ip-address is the IP address of the access
server and line# is the two-digit line number of the
modem, prefixed by 20. (For example, enter
telnet 172.0.0.1 2001 if the IP address is 172.0.0.1 and
the modem line number is 1.) If you do not know which
line number to use, enter the show line command and
check the resulting display for tty numbers that have
inout in the Modem column. Use one of those
Trying 172.0.0.1, 2001 ... Open numbers.
The Telnet connection is open when the word Open
appears.
Step 2 at There is no command prompt in AT command mode.
OK To confirm that you can enter AT commands, enter at
and press Return. If you are in AT command mode, the
modem returns OK.
Step 3 Ctrl-Shift-6 X When you have finished entering AT commands, exit
AT command mode and return to privileged EXEC
mode. To do so, enter Ctrl-Sh-6 X (that is, hold down
the Control and Shift keys and press 6, and then
release everything and press X).
# disconnect
Enter disconnect to end the Telnet connection.

Use these guidelines when you send AT commands to a modem:

• Enter the AT prefix before all commands except A/ (Repeat Last Command) and +++ (Escape code).
Commands are carried out when you press Return or Enter.
• Command lines are limited to 128 characters, not including the AT prefix and Return characters.
Dial strings, however, are limited to 49 characters.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 Entering AT Commands

• You can enter several commands on the same command line, as long as you do not exceed the
128-character limit (see preceding item). Enter commands with no spaces or separators between
them. The commands are carried out in the order in which they appear on the command line. If an
individual command fails (returns ERROR), any subsequent commands on that line are not carried
out.
• Certain commands work only if they are the last command on the line. Such commands include
A (answer), D (dial), H (hang up), Z (reset), and any command that takes time to execute or that
does not return a result immediately.
• Spaces within AT commands are permitted anywhere except between the A and the T. For example,
enter ATS0?, AT S0?, ATS 0?, but not A TS0?.
• Enter commands as either uppercase or lowercase, not mixed case.
• Enter Ctrl-C (^C) to abort a partially entered command. The modem echoes ^C.
• Use the Backspace key (or another key specified in register S5) to erase characters on the command
line, except for the leading characters AT. To clear the characters AT, press Return for a fresh
command line. For information on changing the command-line erase key, see the “S5 - Backspace
Character” section on page 77.
• A missing numeric argument is assumed to be zero. For example, the Quiet command Q is
equivalent to Q0.
• The modem operates in the following modes:
– Command state: The modem is idle and waiting for commands.
– Set-up state: Establishing a connection.
– Online state: Connected to another modem. To return to the online state from any other state,
enter ATO and press Return. A fresh connect message is sent.
– Escape state: Allows you to enter commands while the modem is on line. To go to escape state,
enter +++ (+++ is the default escape code; see “S2 - Escape Character,” on page 76 for details
on changing the escape code). When you enter the +++ command, pause for at least a second
before and after typing it, but do not pause between characters. Do not press Return. Wait for
the OK prompt before entering commands.
The escape code can be enabled and disabled; for instructions, see “S2 - Escape Character,” on
page 76 .

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 Command Syntax

Command Syntax

DTE/DCE Command-Response Protocol

Communication between the DTE and modem (DCE) follows command-response protocol, i.e., the DTE
sends a command to the modem, then waits for a response from the modem.

Command Syntax and Guidelines

DTE Commands
The ISO 646 character set (CCITT T.50 International Alphabet 5, American Standard Code for
Information Interchange) is used for the issuance of commands and responses. Only the low-order 7 bits
of each character are used for commands or parameters; the high-order bit is ignored. Upper case
characters are equivalent to lower case characters.

DTE Command Lines

A command line is a string of characters sent from a DTE to the DCE while the DCE is in a command
state. Command lines have a prefix, a body, and a terminator. The prefix consists of the ASCII characters
“AT” (41h, 54h) or “at” (61h, 74h). The body is a string of commands restricted to printable ASCII
characters (20h - 7Eh). Space characters (ASCII 20h) and control characters other than carriage return
<CR> (default value = ASCII 013 = 0Dh, see register S3), backspace <BS> (default value = ASCII 008
= 08h, see register S5), and cancel <cntrl-x> (ASCII 024 = 18h) in the command string are ignored. The
default terminator is the <CR> character. Characters that precede the AT prefix are ignored.

AT Command Guidelines
Modem operation is controlled by generic AT commands. These AT commands may be basic AT (i.e.,
commands preceded by AT, AT&, AT%, AT*, AT\, AT), AT-, or AT#), S-Register (e.g., S6=n) or Fax
class 2 (e.g., +FDCS:) commands. The command syntax and operation guidelines governing each of
these command categories are described in subsequent sections.

Basic Command Syntax

Characters within the command line are parsed as commands with associated parameter values. The
basic commands consist of single ASCII characters, or single characters proceeded by a prefix character,
followed by a decimal parameter (e.g., “&D1”). Missing decimal parameters are evaluated as 0.

+ Command Termination
A “+” command must be terminated by the semicolon “;” character (ASCII 3Bh) if in a command string
prior to another command, or by the <CR> at the end of the command string.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Command Set Summary

AT Command Set Summary

Basic AT Commands

Command Function
A/ Re-execute command
A Go off-hook and attempt to answer a call.
B0 Select V.22 connection at 1200 bps.
B1 Select Bell 212A connection at 1200 bps.
C1 Return OK message.
Dn Dial modifier.
E0 Turn off command echo.
E1 Turn on command echo.
H0 Initiate a hang-up sequence.
H1 If on-hook, go off-hook and enter command mode.
I0 Report product code.
I1 Report pre-computed checksum.
I2 Report OK.
I3 Report firmware revision, model, and interface type.
I4 Report response programmed by an OEM.
I5 Report the country code parameter.
I6 Report modem data pump model and code revision.
I7 Report OK.
N0 Turn off automode detection.
N1 Turn on automode detection.
O0 Go on-line.
O1 Go on-line and initiate a retrain sequence.
P Force pulse dialing.
Q0 Allow result codes to DTE.
Q1 Inhibit result codes to DTE.
Sn Select S-Register as default.
Sn? Return the value of S-Register n.
=v Set default S-Register to value v.
? Return the value of default S-Register.
T Force DTMF dialing.
V0 Report short form (terse) result codes.
V1 Report long form (verbose) result codes.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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AT Command Set Summary

Command Function
W0 Report DTE speed in EC mode.
W1 Report line speed, EC protocol and DTE speed.
W2 Report DCE speed in EC mode.
X0 Report basic call progress result codes, i.e., OK, CONNECT, RING, NO CARRIER
(also, for busy, if enabled, and dial tone not detected), NO ANSWER and ERROR.
X1 Report basic call progress result codes and connections speeds (OK, CONNECT,
RING, NO CARRIER (also, for busy, if enabled, and dial tone not detected), NO
ANSWER, CONNECT XXXX, and ERROR.
X2 Report basic call progress result codes and connections speeds, i.e., OK, CONNECT,
RING, NO CARRIER (also, for busy, if enabled, and dial tone not detected), NO
ANSWER, CONNECT XXXX, and ERROR.
X3 Report basic call progress result codes and connection rate, i.e., OK, CONNECT,
RING, NO CARRIER, NO ANSWER, CONNECT XXXX, BUSY, and ERROR.
X4 Report all call progress result codes and connection rate, i.e., OK, CONNECT, RING,
NO CARRIER, NO ANSWER, CONNECT XXXX, BUSY, NO DIAL TONE and
ERROR.
Y0 Disable long space disconnect before on-hook.
Y1 Enable long space disconnect before on-hook.
Z0 Restore default profile after warm reset.
Z1 Restore default profile after warm reset.

&C0 Force RLSD active regardless of the carrier state.

&C1 Allow RLSD to follow the carrier state.
&D0 Interpret DTR ON-to-OFF transition per &Qn:
• &Q0, &Q5, &Q6
– The modem ignores DTR
• &Q1, &Q4
– The modem hangs up
• &Q2, &Q3
– The modem hangs up
&D1 Interpret DTR ON-to-OFF transition per &Qn:
• &Q0, &Q1, &Q4, &Q5, &Q6
– Asynchronous escape
• &Q2, &Q3
– The modem hangs up
&D2 Interpret DTR ON-to-OFF transition per &Qn:
• &Q0 through &Q6
– The modem hangs up

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Command Set Summary

Command Function
&D3 Interpret DTR ON-to-OFF transition per &Qn:
• &Q0, &Q1, &Q4, &Q5, &Q6
– The modem performs soft reset
• &Q2, &Q3
– The modem hangs up
&F0 Restore factory configuration.
&F1 Restore factory configuration.
&G0 Disable guard tone.
&G1 Disable guard tone.
&G2 Enable 1800 Hz guard tone.
&L0 Select dial up line operation.
&M0 Select direct asynchronous mode.
&M1 Select sync connect with async off-line command mode (serial interface operation
only).
&M2 Select sync connect with async off-line command mode and enable DTR dialing of
directory zero (serial interface operation only).
&M3 Select sync connect with async off-line command mode and enable DTR to act as
Talk/Data switch (serial interface operation only).
&Q0 Select direct asynchronous mode.
&Q1 Select sync connect with async off-line command mode (serial interface operation
only).
&Q2 Select sync connect with async off-line command mode and enable DTR dialing of
directory zero (serial interface operation only).
&Q3 Select sync connect with async off-line command mode and enable DTR to act as
Talk/Data switch (serial interface operation only).
&Q4 Reserved.
&Q5 Modem negotiates an error corrected link.
&Q6 Select asynchronous operation in normal mode.
&R0 CTS tracks RTS (async) or acts per V.25 (sync).
&R1 CTS is always active.
&S0 DSR is always active.
&S1 DSR acts per V.25.
&T0 Terminate any test in progress.
&T1 Initiate local analog loopback.
&T2 Returns ERROR result code.
&T3 Initiate local digital loopback.
&T4 Allow remote digital loopback.
&T5 Disallow remote digital loopback request.
&T6 Request an RDL without self-test.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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AT Command Set Summary

Command Function
&T7 Request an RDL with self-test.
&T8 Initiate local analog loop with self-test.
&V Display current configurations.
&V1 Display connection statistics
&W0 Report OK
&W1 Report OK

&X0 Select internal timing for the transmit clock.

&X1 Select external timing for the transmit clock.
&X2 Select slave receive timing for the transmit clock.
&Y0 Recall stored profile 0 upon power up.
&Y1 Recall stored profile 1 upon power up.
&Zn=x Store dial string x (to 34) to location n (0 to 3).

%E0 Disable line quality monitor and auto retrain.

%E1 Enable line quality monitor and auto retrain.
%E2 Enable line quality monitor and fallback/fall forward.
%L Return received line signal level.
%Q Report the line signal quality.

\Kn Controls break handling during three states:

1. When modem receives a break from the DTE:
\K0,2,4 Enter on-line command mode, no break sent to the remote modem.
\K1 Clear buffers and send break to remote modem.
\K3 Send break to remote modem immediately.
\K5 Send break to remote modem in sequence with transmitted data.
2. When modem receives \B in on-line command state:
\K0,1 Clear buffers and send break to remote modem.
\K2,3 Send break to remote modem immediately.
\K4,5 Send break to remote modem in sequence with transmitted data.
3. When modem receives break from the remote modem:
\K0,1 Clear data buffers and send break to DTE.
\K2,3 Send a break immediately to DTE.
\K4,5 Send a break with received data to the DTE.

\N0 Select normal speed buffered mode.

\N1 Select direct mode.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Command Set Summary

Command Function
\N2 Select reliable link mode.
\N3 Select auto reliable mode.
\N4 Force LAPM mode.
\N5 Force MNP mode.
\V0 Connect messages are controlled by the command settings X, W, and S95.
\V1 Connect messages are displayed in the single line format.

+CTD Enables and disables tone detection

+IPT ISDN Protocol Selection
+ISP Selects Pass-Through Mode or POTS Modem Connection
+MS Select modulation.
+PTF Sets up frequencies to be detected for each filter 0 - 15
+QTR? Queries detected tone
+TSA Program the Time Slot Assignment
+VTS Generates single/dual tones

V.92 Data Mode Commands

Command Function
+QC V.92 QuickConnect Enable
+HEN Modem On-Hold Enable
+HTL Modem On-Hold Time-Out Setting
+DS44 V.44 Compression Parameters
+DCS V.42bis/V.44 Negotiation Enable
%Cn Enable/Disable Data Compression Negotiation (see ECC Commands)
&V2 V.92 connection statistics

ECC Commands

Command Function
%C0 Disable data compression.
%C1 Enable MNP 5 data compression negotiation.
%C2 Enable V.42 bis data compression negotiation.
%C3 Enable both V.42 bis and MNP 5 compression negotiation.
%C4 Forces V.44 data compression negotiation with fallback to no data compression.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Command Set Summary

Command Function
%C5 Allows V.44 data compression negotiation and fallback to V.42 bis and MNP 5 data
compression negotiation the same as %C3 (Default).

\A0 Set maximum block size in MNP to 64.

\A1 Set maximum block size in MNP to 128.
\A2 Set maximum block size in MNP to 192.
\A3 Set maximum block size in MNP to 256.

MNP10EC Commands

Command Function
-SEC=0 Disable MNP10-EC.
-SEC=1,[<tx Enable MNP10-EC and set transmit level <tx level> 0 to 30 (0 dBm to -30 dBm).
level>]

FAX Class 2 Commands

Command Function
+FCLASS=n Service class.
+FAA=n Adaptive answer.
+FAXERR Fax error value.
+FBOR Phase C data bit order.
+FBUF? Buffer size (read only).
+FCFR Indicate confirmation to receive.
+FCLASS= Service class.
+FCON Facsimile connection response.
+FCIG Set the polled station identification.
+FCIG: Report the polled station identification.
+FCR Capability to receive.
+FCR= Capability to receive.
+FCSI: Report the called station ID.
+FDCC= DCE capabilities parameters.
+FDCS: Report current session.
+FDCS= Current session results.
+FDIS: Report remote capabilities.
+FDIS= Current sessions parameters.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Command Function
+FDR Begin or continue phase C receive data.
+FDT= Data transmission.
+FDTC: Report the polled station capabilities.
+FET: Post page message response.
+FET=N Transmit page punctuation.
+FHNG Call termination with status.
+FK Session termination.
+FLID= Local ID string.
+FLPL Document for polling.
+FMDL? Identify model.
+FMFR? Identify manufacturer.
+FPHCTO Phase C time out.
+FPOLL Indicates polling request.
+FPTS: Page transfer status.
+FPTS= Page transfer status.
+FREV? Identify revision.
+FSPL Enable polling
+FTSI: Report the transmit station ID.

AT Commands Description
• AT Commands, page 11
• AT& Commands, page 22
• AT% Commands, page 44
• AT\ Commands, page 46
• AT+ Commands, page 48

AT Commands

A/ - Re-execute Command
The modem behaves as though the last command line had been re-sent by the DTE. "A/" will repeat all
the commands in the command buffer.
The principal application of this command is to place another call (using the Dial command) that failed
to connect due to a busy line, no answer, or a wrong number. This command must appear alone on a
command line. This command should not be terminated by a carriage return.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

AT= x - Write to Selected S-Register

This command writes the value x to the currently selected S-Register. An S-Register can be selected by
using the ATSn command. All of the S-Registers will return the OK response if x is a number. Some
registers may not be written due to country specific PTT limitations.

Result Code Meaning

OK For all arguments

AT? - Read Selected S-Register

This command reads and displays the selected S-Register. An S-Register can be selected by
using the ATSn command.

Result Code Meaning

OK For all arguments

A - Answer
The modem will go off-hook and attempt to answer an incoming call if correct conditions are met. Upon
successful completion of answer handshake, the modem will go on-line in answer mode. Operation is
also dependent upon +FCLASS command and country-specific requirements.
If +FCLASS=0 is selected, the modem will enter the connect state after exchanging carrier with the
remote modem. If no carrier is detected within a period specified in register S7, the modem hangs up.
Any character entered during the connect sequence will abort the connection attempt.
If +FCLASS= 2 is selected, the modem will go off-hook in V.21 answer mode. It will generate the V.21
2100 Hz answer tone for 3 ± 0.5 seconds and, following a delay of 70 ms, will proceed as if the +FTH=3
command were issued. At any stage up to (but excluding) the +FTH=3 command state, any character will
abort the communication. (See the description of the +FTH command for details.)

Bn - CCITT or Bell
When the modem is configured to allow either option, the modem will select Bell or CCITT modulation
for a line speed connection of 300 or 1200 bps according to the parameter supplied. Any other line speed
will use a CCITT modulation standard. The parameter value, if valid, is written to S27 bit 6.

Parameter Value Meaning

B0 Selects CCITT operation at 300 or 1200 bps during Call Establishment and a
subsequent connection.
B1 Selects BELL operation at 300 or 1200 bps during Call Establishment and a
subsequent connection.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Dn - Dial
This command directs the modem to go on-line, dial according to the string entered and attempt to
establish a connection. If no dial string is supplied, the modem will go on-line and attempt the handshake
in originate mode.

Note If the ATD command is issued before the S1 register has cleared, the modem will respond with the NO
CARRIER result code.

If +FCLASS=0 is selected, the modem will behave as a data modem and will attempt to connect to
another data modem. The modem will have up to the period of time specified by register S6 or S7 to wait
for carrier and complete the handshake. If this time expires before the modem can complete the
handshake, the modem will go on-hook with the NO CARRIER response. This command will be aborted
in progress upon receipt of any DTE character before completion of the handshake.
If +FCLASS= 2 is selected, the modem will behave as a facsimile modem and attempt to connect to a
facsimile machine (or modem) by entering the HDLC V.21 channel 2 receive state (as if +FRH=3 had
been issued). This command will be aborted upon receipt of any DTE character if the modem has not
finished dialing. In this case, the modem will go on-hook and return to command mode after displaying
the NO CARRIER message. If the modem has finished dialing, it proceeds as if the +FRH=3 command
has been issued. (Refer to the +FRH command to determine how the modem behaves following this
stage.)

Dial Modifiers
The valid dial string parameters are described below. Punctuation characters may be used for clarity, with
parentheses, hyphen, and spaces being ignored.

Dial Modifier Meaning

0-9 DTMF digits 0 to 9.
* The 'star' digit (tone dialing only).
# The 'gate' digit (tone dialing only).
A-D DTMF digits A, B, C, and D. Some countries may prohibit sending these digits
during dialing.
T Select tone dialing: tone dial the numbers that follow.
, Dial pause: the modem will pause for one second before dialing the digits
following “,”. Longer pauses may be acheived by using more than one “,”.
<i> Invalid character:: unspecified behavior.

En - Command Echo
The modem enables or disables the echo of characters to the DTE according to the parameter supplied.
The parameter value, if valid, is written to S14 bit 1.

Parameter Value Meaning

E0 Disables command echo.
E1 Enables command echo. (Default)

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

Hn - Disconnect (Hang-Up)
This command initiates a hang up sequence.
This command may not be available for some countries due to PTT restrictions.

Parameter Value Meaning

H0 The modem will release the line if the modem is currently on-line, and will
terminate any test (AT&T) that is in progress. Country specific, modulation
specific, and error correction protocol specific (S38) processing is handled
outside of the H0 command.
H1 If on-hook, the modem will go off-hook and enter command mode. For US
models, the modem will remain off-hook.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

In - Identification
The modem reports to the DTE the requested result according to the command parameter.

Parameter Value Meaning

I0 Reports product code. Example: XXX ARM CSM
I1 Calculates the code checksum and reports the least significant word (16 bits) of
the checksum in decimal.
I2 Report OK
I3 Reports the firmware version.
I4 Response can be configured using CMDDAT and CMDREQ messages.
I5 Reports Country Code parameter. Example: 022
I6 Reports modem data pump model, internal ROM code revision, and RAM code
revision. Example: RL56DDP L8565A Rev 47.22/47.22
I7 Reports OK

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Result Code Meaning

OK n = 0 to 7
ERROR Otherwise

Nn - Automode Enable
This command enables or disables automode detection. The parameter value, if valid, is written to S31
bit 1.

Parameter Value Meaning

N0 Automode detection is disabled (equivalent to setting the +MS <automode>
subparameter to 0). A subsequent handshake will be conducted according to the
contents of S37 or, if S37 is zero, according to tms <mod><min><max>
parameters.
N1 Automode detection is enabled (equivalent to setting the +MS <automode>
subparameter to 1). A subsequent handshake will be conducted according the
automode algorithm supported by the modem, e.g., according to the contents of
S37 or, if S37 is zero, starting at the highest enabled modulation. (Default)

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

Note • The Nn and S37=x commands override the +MS command settings. When the N0 or N1 command
is issued, the +MS subparameters are updated to reflect the Nn and S37 values (see +MS command
and S37 register).
For example:
N1S37=10 updates the +MS command subparameters to reflect +MS=10,1,300,12000
N0S37=10 updates the +MS command subparameters to reflect +MS=10,0,12000,12000
• Use of the +MS command is recommended instead of the Nn and S37=x commands. Nn and S37=x
commands are supported for compatibility with existing communication software.

On - Return to On-Line Data Mode

This command determines how the modem will enter the on-line data mode. If the modem is in the
on-line command mode, the enters the on-line data mode with or without a retrain. If the modem is in
the off-line command mode (no connection), ERROR is reported.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Parameter Value Meaning

O0 Enters on-line data mode without a retrain. Handling is determined by the Call
Establishment task. Generally, if a connection exists, this command connects the
DTE back to the remote modem after an escape (+++).
O1 Enters on-line data mode with a retrain before returning to on-line data mode.
O2 Same as O0
O3 Enters on-line data mode with a rate reneg (no speed shift) before returning to
on-line data mode.
O4 Enters on-line data mode with a rate reneg and one speed shift downward before
returning to on-line data mode.
O5 Enters on-line data mode with a rate reneg and one speed shift upward before
returning to on-line data mode.

Result Code Meaning

OK n = 0 to 5 and a connection exists.
ERROR Otherwise

P - Set Pulse Dial Default

This command is included for compatibility only, and has no effect other than returning a result code.
Result Code: OK

Qn - Quiet Results Codes Control

The command enables or disables the sending of result codes to the DTE according to the parameter
supplied. The parameter value, if valid, is written to S14 bit 2.

Parameter Value Meaning

Q0 Enables result codes to the DTE. (Default)
Q1 Disables result codes to the DTE.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

Sn - Select S-Register
The modem selects an S-Register or performs an S-Register read or write function.

AT Command Set and Register Summary for Cisco PVDM2 Digital Modems
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 AT Commands Description

Parameter Value Meaning

n Establishes S-Register n as the last register accessed.
n=v Sets S-Register n to the value v.
n? Reports the value of S-Register n.

The parameter n can be omitted, in which case the last S-Register accessed will be assumed. The S can
be omitted for AT= and AT?, in which case the last S-Register accessed will be assumed.

Command Example Meaning

ATS7 establishes S7 as the last accessed register.
AT=40 sets the contents of the last register accessed to 40.
ATS=20 sets the contents of the last register accessed to 20.

If the number "n" is beyond the range of the S-Registers available, the modem will return the ERROR
message. The value "v" is "MOD"ed with 256. If the result is outside the range permitted for a given
S-Register the values will still be stored, but functionally the lower and higher limits will be observed.
Input and output are always in decimal format. Note that some S-Registers are read-only. In these cases,
writing to the S-Register will appear to be accepted but the value will not actually be written.
Due to country restrictions, some commands will be accepted, but the value may be limited and replaced
by a maximum or minimum value.

T - Set Tone Dial Default

This command is included for compatibility only, and has no effect other than returning a result code.
Result Code: OK

Vn - Result Code Form

This command selects the sending of short-form or long-form result codes to the DTE. The parameter,
if valid, is written to S14 bit 3.

Parameter Value Meaning

V0 Enables short-form (terse) result codes. Line feed is not issued before a
short-form result code.
V1 Enables long-form (verbose) result codes. (Default)

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

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 AT Commands Description

Wn - Connect Message Control

This command controls the format of CONNECT messages. The parameter value, if valid, is written to
S31 bits 2 and 3. Note that the Wn command can be overridden by register S95 bits (see S95 description).

Parameter Value Meaning

W0 Upon connection, the modem reports only the DTE speed (e.g., CONNECT
19200). Subsequent responses are disabled. (Default)
W1 Upon connection, the modem reports the line speed, the error correction
protocol, and the DTE speed, respectively. Subsequent responses are disabled.
W2 Upon connection, the modem reports the DCE speed (e.g., CONNECT 14400).
Subsequent responses are disabled.

Result Code Meaning

OK n = 0, 1, or 2
ERROR Otherwise

Xn - Extended Result Codes

This command selects which subset of the result messages will be used by the modem to inform the DTE
of the results of commands.
Blind dialing is enabled or disabled by country parameters. If the user wishes to enforce dial tone
detection, a "W" can be placed in the dial string (see D command). Note that the information below is
based upon the default implementation of the X results table. Table 1 indicates the messages which are
enabled for each X value.
If the modem is in facsimile mode (+FCLASS= 2), the only message sent to indicate a connection is
CONNECT without a speed indication.

Parameter Value Meaning

X0 Disables monitoring of busy tones unless forced otherwise by country
requirements; send only OK, CONNECT, RING, NO CARRIER, ERROR, and
NO ANSWER result codes. Blind dialing is enabled/disabled by country
parameters. If busy tone detection is enforced and busy tone is detected, NO
CARRIER will be reported. If dial tone detection is enforced or selected and dial
tone is not detected, NO CARRIER will be reported instead of NO DIAL TONE.
The value 000b is written to S22 bits 6, 5, and 4, respectively.
X1 Disables monitoring of busy tones unless forced otherwise by country
requirements; send only OK, CONNECT, RING, NO CARRIER, ERROR, NO
ANSWER, and CONNECT XXXX (XXXX = rate). Blind dialing
enabled/disabled by country parameters. If busy tone detection is enforced and
busy tone is detected, NO CARRIER will be reported instead of BUSY. If dial
tone detection is enforced or selected and dial tone is not detected, NO
CARRIER will be reported instead of NO DIAL TONE. The value 100b is
written to S22 bits 6, 5, and 4, respectively.

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 AT Commands Description

Parameter Value Meaning

X2 Disables monitoring of busy tones unless forced otherwise by country
requirements; send only OK, CONNECT, RING, NO CARRIER, ERROR, NO
DIALTONE, NO ANSWER, and CONNECT XXXX. If busy tone detection is
enforced and busy tone is detected, NO CARRIER will be reported instead of
BUSY. If dial tone detection is enforced or selected and dial tone is not detected,
NO DIAL TONE will be reported instead of NO CARRIER. The value 101b is
written to S22 bits 6, 5, and 4, respectively.
X3 Enables monitoring of busy tones; send only OK, CONNECT, RING, NO
CARRIER, ERROR, NO ANSWER, and CONNECT XXXX. Blind dialing is
enabled/disabled by country parameters. If dial tone detection is enforced and
dial tone is not detected, NO CARRIER will be reported. The value 110b is
written to S22 bits 6, 5, and 4, respectively.
X4 Enables monitoring of busy tones; send all messages. The value 111b is written
to S22 bits 6, 5, and 4, respectively. (Default)

Result Code Meaning

OK n = 0 to 4
ERROR Otherwise

Table 1 Extended Result Codes

Short Form Long Form n Value in ATXn Command

0 1 2 3 4
0 OK x x x x x
1 CONNECT x x x x x
2 RING x x x x x
3 NO CARRIER x x x x x
4 ERROR x x x x x
5 CONNECT 1200 1 x x x x
6 NO DIALTONE 3 3 x x x
7 BUSY 3 3 3 x x
8 NO ANSWER x x x x x
9 CONNECT 0600 1 x x x x
10 CONNECT 2400 1 x x x x
11 CONNECT 4800 1 x x x x
12 CONNECT 9600 1 x x x x
13 CONNECT 7200 1 x x x x
14 CONNECT 12000 1 x x x x
15 CONNECT 14400 1 x x x x
16 CONNECT 19200 1 x x x x
17 CONNECT 38400 1 x x x x
18 CONNECT 57600 1 x x x x
19 CONNECT 115200 1 x x x x
20 CONNECT 230400 x x x x x

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 AT Commands Description

Table 1 Extended Result Codes (continued)

Short Form Long Form n Value in ATXn Command

0 1 2 3 4
22 CONNECT 75TX/1200RX 1 x x x x
23 CONNECT 1200TX/75RX 1 x x x x
24 DELAYED 4 4 4 4 x
32 BLACKLISTED 4 4 4 4 x
33 FAX x x x x x
35 DATA x x x x x
40 CARRIER 300 x x x x x
44 CARRIER 1200/75 x x x x x
45 CARRIER 75/1200 x x x x x
46 CARRIER 1200 x x x x x
47 CARRIER 2400 x x x x x
48 CARRIER 4800 x x x x x
49 CARRIER 7200 x x x x x
50 CARRIER 9600 x x x x x
51 CARRIER 12000 x x x x x
52 CARRIER 14400 x x x x x
53 CARRIER 16800 x x x x x
54 CARRIER 19200 x x x x x
55 CARRIER 21600 x x x x x
56 CARRIER 24000 x x x x x
57 CARRIER 26400 x x x x x
58 CARRIER 28800 x x x x x
59 CONNECT 16800 1 x x x x
61 CONNECT 21600 1 x x x x
62 CONNECT 24000 1 x x x x
63 CONNECT 26400 1 x x x x
64 CONNECT 28800 1 x x x x
66 COMPRESSION: CLASS 5 x x x x x
67 COMPRESSION: V.42 bis x x x x x
69 COMPRESSION: NONE x x x x x
70 PROTOCOL: NONE x x x x x
77 PROTOCOL: LAPM x x x x x
78 CARRIER 31200 x x x x x
79 CARRIER 33600 x x x x x
80 PROTOCOL: ALT x x x x x
81 PROTOCOL: ALT-CELLULAR x x x x x
84 CONNECT 33600 1 x x x x
91 CONNECT 31200 1 x x x x
110 V110 x x x x x
120 V120 MuItiframe I mode x x x x x
121 V120 UI unacknowledged x x x x x
150 CARRIER 32000 x x x x x
151 CARRIER 34000 x x x x x

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 AT Commands Description

Table 1 Extended Result Codes (continued)

Short Form Long Form n Value in ATXn Command

0 1 2 3 4
152 CARRIER 36000 x x x x x
153 CARRIER 38000 x x x x x
154 CARRIER 40000 x x x x x
155 CARRIER 42000 x x x x x
156 CARRIER 44000 x x x x x
157 CARRIER 46000 x x x x x
158 CARRIER 48000 x x x x x
159 CARRIER 50000 x x x x x
160 CARRIER 52000 x x x x x
161 CARRIER 54000 x x x x x
162 CARRIER 56000 x x x x x
165 CONNECT 32000 x x x x x
166 CONNECT 34000 x x x x x
167 CONNECT 36000 x x x x x
168 CONNECT 38000 x x x x x
169 CONNECT 40000 x x x x x
170 CONNECT 42000 x x x x x
171 CONNECT 44000 x x x x x
172 CONNECT 46000 x x x x x
173 CONNECT 48000 x x x x x
174 CONNECT 50000 x x x x x
175 CONNECT 52000 x x x x x
176 CONNECT 54000 x x x x x
177 CONNECT 56000 x x x x x
+F4 +FCERROR x x x x x

Note An 'x' in a column indicates that the message (either the long form if verbose, or the value only
for short form) will be generated when that particular value of 'n' (shown at the top of the
column) has been selected by the use of ATXn. If the column is blank, then no message will
be generated for that x option. A numeral indicates which less explicit message (verbose or
short form) will be output for that X option. (Also, see Section Error Detection and Data
Compression Commands).

Yn - Long Space Disconnect

This command enables/disables the generation and response to long space disconnect. The parameter
value, if valid, is written to S21 bit 7.

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 AT Commands Description

Parameter Value Meaning

Y0 Disables long space disconnect. (Default)
Y1 Enables long space disconnect. In non-error correction mode, the modem will
send a long space of four seconds prior to going on-hook. In non-error correction
mode, the modem will respond to the receipt of a long space (i.e., a break signal
greater than 1.6 seconds) by going on-hook.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

Zn - Soft Reset and Restore Profile

The modem performs a soft reset and restores (recalls) the default profile. If no parameter is specified,
zero is assumed. There is only one default profile and ATZ0 and ATZ1 restores the same default profile.

Parameter Value Meaning

Z0 Soft reset and restore default profile.
Z1 Soft reset and restore default profile.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

AT& Commands

&Cn - RLSD (DCD) Option

The modem controls the RLSD output in accordance with the parameter supplied. The parameter value,
if valid, is written to S21 bit 5.

Parameter Value Meaning

&C0 RLSD remains ON at all times.
&C1 RLSD follows the state of the carrier. (Default)

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 AT Commands Description

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

&Dn - DTR Option

This command interprets the ON to OFF transition of the DTR signal from the DTE in accordance with
the parameter supplied. The parameter value, if valid, is written to S21 bits 3 and 4. Also, see S25.

Parameter Value Meaning

&D0 DTR drop is interpreted according to the current &Qn setting as follows:
• &Q0, &Q5, &Q6: DTR is ignored (assumed ON). Allows operation with
DTEs which do not provide DTR.
• &Q1, &Q4: DTR drop causes the modem to hang up. Auto-answer is not
affected.
• &Q2, &Q3: DTR drop causes the modem to hang up. Auto-answer is
inhibited.
&D1 DTR drop is interpreted according to the current &Qn setting as follows:
• &Q0, &Q1, &Q4, &Q5, &Q6: DTR drop is interpreted by the modem as if
the asynchronous escape sequence had been entered. The modem returns to
asynchronous command state without disconnecting.
• &Q2, &Q3: DTR drop causes the modem to hang up. Auto-answer is
inhibited.
&D2 DTR drop is interpreted according to the current &Qn setting as follows:
• &Q0 through &Q6: DTR drop causes the modem to hang up. Auto-answer
is inhibited. (Default)
&D3 DTR drop is interpreted according to the current &Qn setting as follows:
• &Q0, &Q1, &Q4, &Q5, &Q6: DTR drop causes the modem to perform a soft
reset as if the Z command were received. The &Y setting determines which
profile is loaded.
• &Q2, &Q3: DTR drop causes the modem to hang up. Auto-answer is
inhibited.

If &Q5, &Q6, +FCLASS=2 is in effect, the action taken is the same as for &Q0.

&Fn - Restore Factory Configuration (Profile)

The modem loads the factory default configuration (profile). The factory defaults are identified for each
command and in the S-Register descriptions. A configuration (profile) consists of a subset of
S-Registers. There is only one factory configuration and AT&F0 and AT&F1 restore the same factory
configuration.

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 AT Commands Description

Parameter Value Meaning

&F0 Restore factory configuration.
&F1 Restore factory configuration.

Result Code Meaning

OK If the modem is not connected
and n = 0 or 1
ERROR If the modem is connected

&Gn - Select Guard Tone

The modem generates the guard tone selected by this command according to the parameter supplied
(DPSK modulation modes only). The parameter value, if valid, is written to S23 bits 6 and 7.

Parameter Value Meaning

&G0 Disables guard tone. (Default)
&G1 Disables guard tone.
&G2 Selects 1800 Hz guard tone.

This command may not be permitted in some countries.

Result Code Meaning

OK n = 0 to 2
ERROR Otherwise

&K - Flow Control

This command is included for compatibility only, and has no effect other than returning a result code.
Result Code: OK

&Ln - Leased Line Operation

This command requests leased line or dial-up operation. This command is provided for compatibility
only; no mode change is performed, dial-up operation continues. The OK response is returned for a valid
parameter, but no other action is performed. The parameter value, if valid, is written to S27 bit 2.

Parameter Value Meaning

&L0 Requests dial-up operation. Dial-up operation continues.

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 AT Commands Description

Result Code Meaning

OK n=0
ERROR Otherwise

&Mn - Asynchronous/Synchronous Mode Selection

This command determines the DTR operating mode. The modem treats the &M command as a subset of
the &Q command.

Parameter Value Meaning

&M0 Selects direct asynchronous operation. Note that the command sequence
&M0\N0 selects normal buffered mode, but the command sequence \N0&M0
selects direct mode. This is because the \N0 command is analogous to the &Q6
command. The value 000b is written to S27 bits 3, 1, and 0, respectively. (See
&Q).
&M1 Selects synchronous connect mode with async off-line command mode. The
value 001b is written to S27 bits 3, 1, and 0, respectively. (Serial interface
operation only.)
&M2 Selects synchronous connect mode with async off-line command mode. Same as
&M1 except that &M2 enables DTR dialing of directory slot 0. The modem will
disconnect if DTR is OFF for more than the period in S25 (in units of hundredths
of a second): the data connection will be synchronous. The value 010b is written
to S27 bits 3, 1, and 0, respectively. (Serial interface operation only.)
&M3 Selects synchronous connect mode. This mode allows DTR to act as a talk/data
switch. The call is manually initiated while DTR is inactive. When DTR becomes
active, the handshake proceeds in originate or answer mode according to S14 bit
7. The value 011b is written to S27 bits 3, 1, and 0, respectively. (Serial interface
operation only.)

Result Code Meaning

OK n = 0 to 3
ERROR Otherwise

&Qn - Sync/Async Mode

This command is an extension of the &M command and is used to control the connection modes
permitted. It is used in conjunction with S36 and S48. (Also, see \N.)

Note When the &Q0 to &Q4 command is issued to select the mode, the subsequent connect message will
report the DCE speed regardless of the W command and S95 settings

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 AT Commands Description

Parameter Value Meaning

&Q0 Selects direct asynchronous operation. The value 000b is written to S27 bits 3, 1,
and 0, respectively. See &M0.
&Q1 Selects synchronous connect mode with async off-line command mode. The
value 001b is written to S27 bits 3, 1, and 0, respectively. See &M1. (Serial
interface operation only.)
&Q2 Selects synchronous connect mode with async off-line command mode and
enables DTR dialing of directory 0. The value 010b is written to S27 bits 3, 1,
and 0, respectively. See &M2. (Serial interface operation only.)
&Q3 Selects synchronous connect mode with async off-line command mode and
enables DTR to act as Talk/Data switch. The value 011b is written to S27 bits 3,
1, and 0, respectively. See &M3. (Serial interface operation only.)
&Q4 Reserved.
&Q5 The modem will try to negotiate an error-corrected link. The modem can be
configured using S36 to determine whether a failure will result in the modem
returning on-hook or will result in fallback to an asynchronous connection. The
value 101b is written to S27 bits 3, 1, and 0, respectively. (Default)
&Q6 Selects asynchronous operation in normal mode (speed buffering). The value
110b is written to S27 bits 3, 1, and 0, respectively.

Result Code Meaning

OK n = 0 to 6
ERROR Otherwise

&Rn - RTS/CTS Option

This selects how the modem controls CTS. CTS operation is modified if hardware flow control is
selected (see &K command). The parameter value, if valid, is written to S21 bit 2.

Parameter Value Meaning

&R0 In sync mode, CTS tracks the state of RTS; the RTS-to-CTS delay is defined by
S26. In async mode, CTS is normally ON and will turn OFF only if required by
flow control.
&R1 In sync mode, CTS is always ON (RTS transitions are ignored). tracks the state
of RTS; In async mode, CTS is normally ON and will turn OFF only if required
by flow control.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

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 AT Commands Description

&Sn - DSR Override

This command selects how the modem will control DSR. The parameter value, if valid, is written to S21
bit 6.

Parameter Value Meaning

&S0 DSR will remain ON at all times. (Default)
&S1 DSR will become active after answer tone has been detected and inactive after
the carrier has been lost.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

&Tn - Test and Diagnostics

The modem will perform selected test and diagnostic functions according to the parameter supplied. A
test can be run only when in an asynchronous operation in non-error-correction mode (normal or direct
mode). To terminate a test in progress, the escape sequence must be entered first, except for parameters
7 and 8. If S18 is non-zero, a test will terminate automatically after the time specified by S18 and display
the OK message. Note: For tests 3, 6, and 7, a connection between the two modems must first be
established.

Parameter Value Meaning

&T0 Terminates test in progress. Clears S16.
&T1 Initiates local analog loopback, V.54 Loop 3. Sets S16 bit 0. If a connection exists
when this command is issued, the modem hangs up. The CONNECT XXXX
message is displayed upon the start of the test.
&T2 Returns ERROR.
&T3 Initiates local digital loopback, V.54 Loop 2. Sets S16 bit 2. If no connection
exists, ERROR is returned. Sets S16 bit 4 when the test is in progress.
&T4 Enables digital loopback acknowledgment for remote request, i.e., an RDL
request from a remote modem is allowed. Sets S23 bit 0.
&T5 Disables digital loopback acknowledgment for remote request, i.e., an RDL
request from a remote modem is denied. Clears S23 bit 0. (Default)
&T6 Requests a remote digital loopback (RDL), V.54 Loop 2, without self test. If no
connection exists, ERROR is returned. Sets S16 bit 4 when the test is in progress.
The CONNECT XXXX message is displayed upon the start of the test.

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 AT Commands Description

Parameter Value Meaning

&T7 Requests a remote digital loopback (RDL),V.54 Loop 2, with self test. (In self
test, a test pattern is looped back and checked by the modem.) If no connection
exists, ERROR is returned. When the test is terminated either via expiration of
S18, or via the &T0 or H command, the number of detected errors is reported to
the DTE. Sets S16 bit 5 when the test is in progress.
&T8 Initiates local analog loopback, V.54 Loop 3, with self test. (In self test, a test
pattern is looped back and checked by the modem.) If a connection exists, the
modem hangs up before the test is initiated. When the test is terminated either
via expiration of S18, or via the &T0 or H command, the number of detected
errors is reported to the DTE. Sets S16 bit 6 when the test is in progress. This
command may not be available in some countries due to PTT restrictions. Note
that a loopback path from TXDATA to RXDATA is required.

&V - Display Current Configuration and Stored Profiles

Reports the current (active) configuration, the stored (user) profiles, and the first four stored telephone
numbers. The stored profiles and telephone numbers are not displayed if the NVRAM is not installed or
is not operational as detected by the NVRAM test during reset processing.
Result Code: OK
Example:
AT&V
ACTIVE PROFILE:
B0 E1 L1 M1 N1 QO T V1 W0 X4 Y0 &C0 &D0 &G2 &J0 &K3 &Q5 &R1 &S0 &T4 &X0 &Y0
S00:002 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:030 S08:002 S09:006
S10:014 S11:255 S12:050 S18:000 S25:005 S26:001 S36:007 S37:000 S38:020 S46:138
S48:007 S95:000

&V1 - Display Last Connection Statistics

Displays the last connection statistics in the following format (shown with typical results):
TERMINATION REASONLINK DISCONNECT or LOCAL REQUEST
LAST TX data rate48000 BPS
HIGHEST TX data rate48000 BPS
LAST RX data rate31200 BPS
HIGHEST RX data rate31200 BPS
Error Correction PROTOCOLLAPM
ModulationV.90
Data COMPRESSIONV42Bis
Digital Pad Detected000
Line QUALITY000
Receive LEVEL023
Highest SPX Receive state068
Highest SPX Transmit state067
Last SPX Receive state000
Last SPX Transmit stateV42Bis
EQM Sum Value0014
RBS Pattern Detected21
Data Rate Dropped in kbps04
Local Retrain Count00
Remote Retrain Count00
Local Rate Reneg Count00
Remote Rate Reneg Count00
Flex 94018302000

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 AT Commands Description

Connected V.90

&V2 - Modem Status Reporting

&V2 reports a string that contains a modem status report.
&V2 responds with a character string organized in the following manner:
BEGINaa26ab26ac26ad26ba11bb11 … ti0END
where:
• The only capitalized letters are BEGIN and END, signifying the start and stop of the message.
• The only small letters are for fields described in this section.
• The only numbers are the values of the fields.
• All values are initialized to 255 or 0, except for ‘qa’ which is initialized to 21 upon power up and
upon the start of each handshake.
• Firmware revisions may add or remove parameters in the &V2 response. Consult the latest firmware
release notes.

Automatic Reporting
By setting bit 4 of S202 (i.e., S202=16), the modem status string will automatically display before every
connect message and after each hang-up (before the ‘NO CARRIER’ message).

Supported &V2 Command Fields

The &V2 Command Fields are described in Table 2. These values are for the US profile; other profiles
are not taken into account.

Table 2 &V2 Command Field Description

Field Code Field Name Field Description

aa Current transmit speed These fields display the data rate codes. These
ab Minimum transmit speed speeds can be decoded using Table 3.

ac Maximum transmit speed

ad Initial transmit speed
ba Current receive speed
bb Minimum receive speed
bc Maximum receive speed
bd Initial receive speed
ca Error correction protocol This field displays the type of error correction
chosen. Refer to Table 4.
cb Data compression type This field displays the type of compression
chosen. Refer to Table 5.
cc Modulation type These fields display the modulation type
cd Initial modulation type chosen, i.e., the DDP CONF value (see DDP
designer’s guide).Refer to Table 6.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

da Symbol rate This field is only for V.34, K56flex, and V.90
connections. For all other connections see the
data pump manual for symbol rate.
Symbol rates are shown in Table 7.
ea Transmit carrier frequency These fields are only for V.34 connections.
eb Receive carrier frequency See Table 8 for a list of frequencies. For all
other connections see the data pump manual
for the carrier frequency. A one signifies the
high frequency and a zero signifies the low
frequency. These are dependent on the symbol
rate which can be found in field “ea”.
fa Last AGC gain value These fields display the decimal value of the
fb Minimum AGC gain value AGC gain high byte. This value can be used to
calculate the Receive level with the
fc Maximum AGC gain value calculations shown in Table 9.
ga Transmit level This field displays the transmit level based on
S91. The value given is in negative dBs.
The Transmit Level in –dB can be calculated
from the reported value as follows:
Transmit Level in –dB = S91 – (0xA48)
gb Transmit Level Reduction This field indicates the transmit level
reduction as requested by the remote modem.
ha Last EQM value These fields display the values from the last,
hb Minimum EQM value maximum and minimum EQM readings.

hc Maximum EQM value

hd Number of EQM hits This field will display the number of times
EQM values became larger than 7Fh. This
condition will cause a rate renegotiation
he EQM Sum (Low Byte) These fields contain the EQM Sum. The
hf EQM Sum (Middle Byte) higher two bytes are used for the speed
selection.
hg EQM Sum (High Byte)
hh Reserved These fields are reserved for future use

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

hj EQM 1 second before &v2 issued or These fields contain the last 1 to 10 seconds of
hangup EQM accumulated
hk EQM 2 seconds before &v2 issued or
hangup
hl EQM 3 seconds before &v2 issued or
hangup
hm EQM 4 seconds before &v2 issued or
hangup
hn EQM 5 seconds before &v2 issued or
hangup
ho EQM 6 seconds before &v2 issued or
hangup
hp EQM 7 seconds before &v2 issued or
hangup
hq EQM 8 seconds before &v2 issued or
hangup
hr EQM 9 seconds before &v2 issued or
hangup
hs EQM 10 seconds before &v2 issued or
hangup
ia SNR ratio These fields display the SNR values obtained
ib Minimum SNR value during the V.34 probe. The value needs to be
converted in the following manner:
ic Maximum SNR value
SNR in dB = 1.7 (X) - 7, where X is the value
displayed
ja Number of local retrains These fields display the number of retrains
jb Number of remote retrains which occurred during the connection.

jc Number of local rate renegs These fields display the number of rate
jd Number of remote rate renegs renegotiations which occurred during the
connection.
je Number of retrains (local and remote) These fields display the number of local and
during V.42 negotiation remote retrains and rate renegs during V.42
jf Number of rate renegs (local and remote) negotiation.
during V.42 negotiation
jg Number of overflow that occurs in any
message queue
ka Transmit Non-linear Encoding These fields display a 1 if non-linear encoding
kb Receive Non-linear Encoding is on and a 0 if non-linear encoding is off.

kc Transmit precoding These fields display a 1if precoding is on and

kd Receive precoding a 0 if precoding is off.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

ke Transmit shaping These fields display a 1 if shaping is on and a
kf Receive shaping 0 if shaping is off.

kg Trellis mapping This field displays the code for the type of
trellis mapping used. Refer to Table 10.
kh Pre-emphasis This field displays the number of the
pre-emphasis filter chosen during the call.
The value will be between 0 and 10.
ki Upper band edge These fields display the upper and lower band
kj Lower band edge edges. The values need to be converted using
the following equations:
Lower -3 dB edge (Hz) = 37.5(X) +150
Upper -3 dB edge (Hz) = 37.5(X) + 2400
where X is the decimal value displayed.
kk Round trip delay high byte These fields display the values needed to
kl Round trip delay low byte calculate the round trip delay using the
following calculation:
RTD =(N/8000) (for V.92 and V.90)
RTD = (N / X) - 3.5 (for V.34, K56flex, and
V.FC)
RTD = (N / 2.4) - 29 (for V.32 bis)
where:
• RTD is the round trip delay in ms,
• N is the decimal value of the 16-bit word
achieved by the combination of the hex
values of the two fields.
• X is the symbol rate found in the field ‘ea’
divided by 1000.
Example:
kk32kl127 converts 32 to 20h and 127 to
7Fh to get the 16-bit word 207Fh. Now
convert this to it’s decimal equivalent (8319)
and this is the value of N.
km Info 0 Sequence (High byte) These fields make up the Info 0 sequence.
kn Info 0 Sequence (Low byte) Convert km to hex -this is the high byte of the
sequence. When kn is converted to hex this is
the low byte of the sequence.
ko RX MP sequence byte 1 (Low byte) These fields make up the RX MP sequence.
kp RX MP sequence byte 1 (High byte) Convert all to hex in this order kqkrkokp.

kq RX MP sequence byte 2 (Low byte)

kr RX MP sequence byte 2 (High byte)

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

la Highest transmit state These fields display the highest transmit and
lb Highest receive state receive SPX states reached. A description of
these states can be found in the DDP
designer’s guide. The values must be changed
to hex format
lc Last transmit state These fields display the last transmit and
ld Last receive state receive SPX states reached. A description of
these states can be found in the DDP
designer’s guide. The values must be changed
to hex format.
le 2nd Last transmit state These fields display the last nth transmit and
lf 2nd Last receive state nth receive spx states reached. A description of
these states can be found in the DDP
lg 3rd Last transmit state designer’s guide. The values must be changed
lh 3rd Last receive state to hex format.
li 4th Last transmit state
lj 4th Last receive state
lk 5th Last transmit state
ll 5th Last receive state
lm 6th Last transmit state
ln 6th Last receive state
lo 7th Last transmit state
lp 7th Last receive state
lq 8th Last transmit state
lr 8th Last receive state
ls 9th Last transmit state
lt 9th Last receive state
lu 10th Last transmit state
lv 10th Last receive state
lw 11th Last transmit state
lx 11th Last receive state
ly 12th Last transmit state
lz 12th Last receive state
ma Connection time (Hours) These fields combine to give the total time of
mb Connection time (Minutes) connection

mc Connection time (Seconds)

na Auto gain amplitude This field displays the auto gain value chosen
for the connection. The amplitude values are
shown in Table 11.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

nb Auto gain attenuation This field displays the auto gain attenuation.
The attenuation values are shown in Table 12.
oa Digital Pad Detected This field displays the digital pad found
during the connection. These fields need to be
converted into its hex equivalent.
The digital pad is determined using Table 13.
ob RBS Pattern This field displays the total RBS pattern found
during the connection.
This field needs to be converted to its hex
equivalent and the lower six bits display the
pattern. Bits 6 and 7 are not used.
oc Rate drop due to RBS This field displays the rate dropped due to
RBS (in kbps).
pa Maximum number of retransmissions for These fields show statistics on the number of
one frame V.42 retransmissions. Frames can also be
pb Total number of retransmissions during referred to as Blocks.
connection
pc Number of LAPM REJ frames received
pd Number of LAPM REJ frames
transmitted
pe Number of TX blocks (High byte) These fields show statistics on the number of
pf Number of TX blocks (Low byte) V.42 data transfers.

pg Number of RX blocks (High byte)

ph Number of RX blocks (Low byte)
pi Number of TX characters (High byte) These fields report the number of characters
pj Number of TX characters (2nd byte) transmitted/received during the connection.

pk Number of TX characters (3rd byte)

pl Number of TX characters (Low byte)
pm Number of RX characters (High byte)
pn Number of RX characters (2nd byte)
po Number of RX characters (3rd byte)
pp Number of RX characters (Low byte)
qa Disconnect reason This field displays a code which describes the
reason for disconnection. Table 14 shows the
disconnect reason codes.
qb Reason for Retrain or rate renegotiation This field displays a code to show where the
last request for a retrain or rate renegotiation
originated from. These codes are given in
Table 15.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

qc ABCODE (Abort code) This field stores the last known ABCODE
received from the data pump.
ra Negotiation Status This field reports the negotiation status. Refer
to Table 16.
rb V.8bis octet 13 This field displays octet 13 from the V.8bis
negotiation. This field represents the
manufacturer’s ID:
148 = K56flex (generic)
74 = Lucent
rc V.8bis octet 14 This field displays octet 14 from the V.8bis
negotiation. This field represents the Licensee
code. Refer to Table 17.
rd V.8bis octet 15 This field displays octet 15 from the V.8bis
negotiation. This field represents the
manufacturer’s product capabilities.
Bit 0: Indicates K56flex capability. (1=
K56flex capable, 0= not K56flex capable)
Bits 1-6: Reserved for future use
Bit 7: Indicates if this octet is the last byte. (1=
last byte, 0= not last byte)
re V.8bis octet 16 This field displays octet 16 from the V.8bis
negotiation. This field represents the flex
version number.
Bits 0-4: Indicate the flex version number
Bit 5: Prototype bit (1=prototype, 0=not
prototype)
Bit 6: Indicates whether the remote is a server
or client (1=server, 0= client)
Bit 7: Indicates if this octet is the last byte.
(1=last byte, 0= not last byte)
rf V.8bis octet 17 This field displays octet 17 from the V.8bis
negotiation. This field represents
CONEXANT’s data pump revision number.
Bits 0-6: Indicate CONEXANT’s data pump
revision number
Bit 7: Indicates if this octet is the last byte.
(1=last byte, o= not last byte)
Note This field is only valid for
CONEXANT-to-XXX connections.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

rg V.8bis octet 18 This field displays octet 18 from the V.8bis
negotiation. This field represents x-law status
and CONEXANT’s controller revision.
Bits 0-4: Indicate CONEXANT’s controller
revision.
Bit 5: Indicates a-law or -law. (1= A-law, 0 =
-law)
Bit 6: Indicates whether x-law was forced or
not. (1=forced, 0= not forced)
Bit 7: Indicates if this octet is the last byte.
(1=last byte, 0 = not last byte)
rh V.8bis progress Bit 0: Set if received Cre Tone
Bit 1: Set if received CRd Tone
Bit2: Set if received CL message
Bit3: Set if received MS message
Bit4: Set if received ACK message
Bit5: Set if received NAK message
Bit6: Set if V.8bis finish
Bit7: Set if V.8 started
sa V.90 Minimum Distance (High Byte) These fields report the high and low bytes of
sb V.90 Minimum Distance (Low Byte) the minimum distance value negotiated in
V.90.
sc V.90 Digital Pad Value (High Byte) These fields display the digital pad value
sd V.90 Digital Pad Value (Low Byte) negotiated in V.90.
2000h is the approximate value for no pad.
2D6Ah is the approximate value for a 3 dB
pad.
3F07h is the approximate value for a 6 dB
pad.
The equation for this calculation is:
20*log10(N/2000h)
Where N is the value from the sc and sd fields.
ta Handshake time This field displays the number of seconds it
took to connect:
tb Number of the handshake retries This field displays the number times the
handshake reached phase three then repeated
to phase two before connecting.
tc EC state 1 Refer to Table 18 for a description of the EC
td EC state 2 state bits.

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Table 2 &V2 Command Field Description (continued)

Field Code Field Name Field Description

te Firmware state These fields show internal error notification.
tf Memory address High byte
tg Memory address Low byte
th Number of minutes since last retrain or
rate reneg
ti WA status This field shows the number of minutes since
the last retrain or rate reneg.

Table 3 Data Rate Codes (&V2 - aa through bd fields)

Transmit/
Value Speed Receive
0 0-300 T/R
1 600 T/R
2 1200 T/R
3 2400 T/R
4 4800 T/R
5 9600 T/R
6 12000 T/R
7 14400 T/R
8 7200 T/R
9 16800 T/R
10 19200 T/R
11 21600 T/R
12 24000 T/R
13 26400 T/R
14 28800 T/R
15 31200 T/R
16 33600 T/R
17 32000 T
18 34000 T
19 36000 T
20 38000 T
21 40000 T
22 42000 T
23 44000 T
24 46000 T

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Table 3 Data Rate Codes (&V2 - aa through bd fields) (continued)

Transmit/
Value Speed Receive
25 48000 T
26 50000 T
27 52000 T
28 54000 T
29 56000 T
30 28000 T
31 29333 T
32 30667 T
33 32000 T
34 33333 T
35 34667 T
36 36000 T
37 37333 T
38 38667 T
39 40000 T
40 41333 T
41 42667 T
42 44000 T
43 45333 T
44 46667 T
45 48000 T
46 49333 T
47 50667 T
48 52000 T
49 53333 T
50 54667 T
51 56000 T
52 Digital 56000 T/R
53 Digital 64000 T/R

Table 4 Error Correction Types (&V2 - ca field)

Value Protocol
70 NONE
77 LAP-M

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Table 4 Error Correction Types (&V2 - ca field)

Value Protocol
80 MNP4
81 MNP10 with cellular

Table 5 Data Compression Types (&V2 - cb field)

Value Compression
69 NONE
66 MNP 5
67 V.42 bis
68 V.44

Table 6 Modulation Types for V.34, K56flex, and V.90 connections (&V2 - cc, cd fields)

224-246 V.90
192-206 V.34
177-184 V.17
161-164 V.23
160 or 168 V.21
144-157 K56flex (K56Plus)1
130-132 V.22 bis
112-120 V.32
98 Bell 212
96 Bell 103
81-82 V.22
64-76 V.FC
49-56 V.33
35 Bell 208
17-20 V.29
1-2 V.27
224-246 V.90
1. Parameter ra can be used to distinguish between K56flex and K56Plus.
For example:
Parameter cc = 000000E0–000000F6: V.90
Parameter cc = 00000090–0000009D and parameter ra bit 5 = 1: K56flex
Parameter cc = 00000090–0000009D and parameter ra bit 5 = 0: K56Plus

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Table 7 Symbol Rates (&V2 - da field)

Value Symbol Rate

0 2400
2 2800
3 3000
4 3200
5 3429

Table 8 Transmit and Receive Carrier Frequencies (&V2 - ea, eb fields)

Symbol Rate High Frequency (Hz) Low Frequency (Hz)

2400 1800 1600
2800 1867 1680
3000 2000 1800
3200 1920 1829
3429 1959 1959

Table 9 Receive Level Calculations for AGC Gain (&V2 - fa, fb, fc fields)

Configuration Calculation1
V.90, K56flex, V.34, V.33, V.17, V.29, V.27, V.FC RL = N/2.7 - 52 dB
V.32 bis, V.32 RL = N/2.7 - 53 dB
V.22 bis, V.22, Bell 212, V.23/1200 RL = N/2.7 - 48 dB
V.21, V.23/75 RL = N/2.7 - 54 dB
Bell 103 RL = N/2.7 - 51 dB
1. Where n is the number displayed

Table 10 Trellis Mapping Values (&V2 - kg field)

Value Trellis Mapping

0 16 state
8 32 state
16 or 24 64 state

Table 11 Auto Gain Amplitude Values (&V2 - na field)

Value Auto Gain (dB)

0 0
2 10

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Table 11 Auto Gain Amplitude Values (&V2 - na field)

Value Auto Gain (dB)

4 15
6 20

Table 12 Auto Gain Attenuation Values (&V2 - nb field)

Value Attenuation (dB)

0 0
16 4

Table 13 Digital Pad Detection (&V2 - oa field)

Bit 7 Bit 6 Pad

0 0 None
0 1 3 dB
1 0 6 dB

Table 14 Disconnection Codes (&V2 - qa field)

Value in Hex Value in Decimal Disconnect Reason

0 0 Normal hangup, no error occurred.
1 1 Reserved.
2 2 Reserved.
3 3 Call Waiting caused disconnect.
4 4 Physical carrier loss.
5 5 No error correction at the other end.
6 6 No response to feature negotiation.
7 7 This modem is async only; the other modem is sync only.
8 8 No framing technique in common.
9 9 No protocol in common.
0A 10 Bad response to feature negotiation.
0B 11 No sync information from the remote modem.
0C 12 Normal hangup initiated by the remote modem.
0D 13 Retransmission limit reached.
0E 14 Protocol violation occurred.
0F 15 Lost DTR.
10 16 Received GSTN cleardown.

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Table 14 Disconnection Codes (&V2 - qa field) (continued)

Value in Hex Value in Decimal Disconnect Reason

11 17 Inactivity timeout.
12 18 Speed not supported.
13 19 Long space disconnect.
14 20 Key abort disconnect.
15 21 Clears previous disconnect reason. (None)
16 22 No connection established.
17 23 Disconnect after three retrains.
18 24 V.42bis expander failure
19 25 Reserved
1A 26 Remote call-waiting
1B 27 Modem on-hold time-out
1C 28 Local request while modem on-hold
1D 29 Local request while FRR

Table 15 Retrain and Rate Renegotiation Codes (&V2 - qb field)

Value Retrain/Renegotiation Reason

0 None
1 Retrain/rate reneg successful
2 Local retrain due to ATO1
3 Local retrain due to high EQM
4 Local rate reneg due to high EQM (FB)
5 Local rate reneg due to low EQM (FF)
6 Local retrain due to 2 consecutive rate renegs
7 Carrier loss but line still looks active
8 Lost connection
9 Fallback to V.34
10 Local rate reneg due to MNP10
11 Local retrain due to MNP10
12 Remote retrain
13 Remote rate reneg
14 V34/2400 retrain
15 V.42 retrain if excessive retransmissions

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Table 16 Negotiation Status (&V2 - ra field)

Bit(s) Description
0 Reserved, reports 0.
1 Indicates RLSD status (1 = RLSD on; 0 = RLSD off).
2 Indicates K56flex/K56Plus Negotiation status (1 = K56flex/K56Plus negotiation
successful; 0 = K56flex/K56Plus negotiation not successful).
3 Reserved, reports 0.
4 Indicates V.90 Negotiation Tried status (1 = V.90 negotiation tried; 0 = V.90
negotiation not tried).
5 Indicates V.90/K56flex (but not K56Plus) Negotiation status (1 = V.90/ K56flex
negotiation successful; 0 = V.90/K56flex negotiation not successful).
6 -7 Reserved, report 0.

Table 17 Licensee Codes (&V2 - rc field)

Value Licensee Code

129 CONEXANT
1 Lucent
128-255 CONEXANT based
0-127 Lucent based

Table 18 EC State Bit Description (&V2 - tc, td fields)

Bit EC State 1 (tc field) EC State 2 (td field)

7 Received ODP Received XID frame
6 Transmitted ODP Transmitted XID frame
5 Received ADP Received SABME frame
4 Transmitted ADP Transmitted SABME frame
3 Received LR frame Received UA frame
2 Transmitted LR frame Transmitted UA frame
1 Received LA frame Switched to sync mode
0 Transmitted LA frame Reserved for future use

&Xn - Select Synchronous Clock Source

Selects the source of the transmit clock for the synchronous mode of operation. The parameter value, if
valid, is written to S27 bits 4 and 5.
In asynchronous mode, the transmit and receive clocks are turned OFF. In synchronous mode, the clocks
are turned ON with the frequency of 1200 Hz or faster corresponding to the speed that is selected for
modem operation.

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Parameter Value Meaning

&X0 Selects internal timing. The modem generates the transmit clock signal and
applies it to the TXCLK output at the serial interface.
&X1 Selects external timing. The local DTE sources the transmit clock signal on the
XTCLK input of the serial interface. The modem applies this clock to the
TXCLK output at the serial interface.
&X2 Selects slave receive timing. The modem derives the transmit clock signal from
the incoming carrier and applies it to the TXCLK output at the serial interface.

Result Code Meaning

OK n = 0 to 2
ERROR Otherwise

&Yn - Designate a Default Reset Profile

Selects which user profile will be used after a hard reset. There is only one factory default profile and
AT&Y0 and AT&Y1 will restore same default profile.

Parameter Value Meaning

&Y0 The modem will use default profile.
&Y1 The modem will use default profile.

Result Code Meaning

OK n = 0 or 1
ERROR Otherwise

&Zn=x - Store Telephone Number

This command is included for compatibility only, and has no effect other than returning a result code.
Result Code: OK

AT% Commands

%En - Enable/Disable Line Quality Monitor and Auto-Retrain or Fallback/Fall Forward

Controls whether or not the modem will automatically monitor the line quality and request a retrain
(%E1) or fall back when line quality is insufficient or fall forward when line quality is sufficient (%E2).
The parameter value, if valid, is written to S41 bits 2 and 6.
If enabled, the modem attempts to retrain for a maximum of 30 seconds.

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Parameter Value Meaning

%E0 Disable line quality monitor and auto-retrain.
%E1 Enable line quality monitor and auto-retrain.
%E2 Enable line quality monitor and fallback/fall forward. (Default)

Result Code Meaning

OK n = 0 to 2
ERROR Otherwise

Fallback/Fall Forward:
When %E2 is active, the modem monitors the line quality (EQM). When line quality is insufficient, the
modem will initiate a rate renegotiation to a lower speed within current modulation. The modem will
keep falling back within the current modulation if necessary until the speed reaches 2400 bps (V.34) or
4800 bps (V.32). Below this rate, the modem will only do retrains if EQM thresholds are exceeded. If
the EQM is sufficient for at least one minute, the modem will initiate a rate renegotiation to a higher
speed within the current modulation speeds. The rate renegotiations will be done without a retrain if a
V.32 bis connection is established.
Speeds attempted during fallback/fall forward are those shown to be available in the rate sequences
exchanged during the initial connection. Fallback/fall forward is available in error correction and normal
modes, but not in direct mode or synchronous mode with external clocks.

%L - Line Signal Level

Returns a value which indicates the received signal level. The value returned is a direct indication (DAA
dependent) of the receive level at the MDP, not at the telephone line connector. For example, 009 = -9
dBm, 043 = -43 dBm, and so on.
Result Code: OK

%Q - Line Signal Quality

Reports the line signal quality. Returns the higher order byte of the EQM value.
An example is as follows.
AT%Q
015

Result Code Meaning

OK If connected.
ERROR If not connected, or connected in
300 bps, V.23, or fax modes.

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AT\ Commands

\Kn - Break Control

Controls the response of the modem to a break received from the DTE or the remote modem or the \B
command according to the parameter supplied. The parameter value, if valid, is written to S40 bits 3, 4,
and 5.
The response is different in depending on three separate cases.

Case 1
The modem receives a break from the DTE when the modem is operating in data transfer mode:

Parameter Value Meaning

\K0 Not supported.
\K1 Not supported.
\K2 Not supported.
\K3 Not supported.
\K4 Not supported.
\K5 Send break to remote modem in sequence with transmitted data. (Default)

Case 2
The second case is where the modem is in the on-line command state (waiting for AT commands during
a data connection, and the \B is received in order to send a break to the remote modem:

Parameter Value Meaning

\K0 Not supported.
\K1 Not supported.
\K2 Not supported.
\K3 Not supported.
\K4 Not supported.
\K5 Send break to remote modem in sequence with data. (Default)

Case 3
The third case is where a break is received from a remote modem during a non-error corrected
connection:

Parameter Value Meaning

\K0 Not supported.
\K1 Not supported.
\K2 Not supported.
\K3 Not supported.

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Parameter Value Meaning

\K4 Not supported.
\K5 Send a break in sequence with received data to DTE. (Default)

Result Code Meaning

OK n = 0 to 5
ERROR Otherwise

\Nn - Operating Mode

This command controls the preferred error correcting mode to be negotiated in a subsequent data
connection.

Parameter Value Meaning

\N0 Selects normal speed buffered mode (disables error-correction mode). (Forces
&Q6.)
\N1 Serial interface selected - Selects direct mode and is equivalent to &M0, &Q0
mode of operation. (Forces &Q0.)
Parallel interface selected - Same as \N0.
\N2 Selects reliable (error-correction) mode. The modem will first attempt a LAPM
connection and then an MNP connection. Failure to make a reliable connection
results in the modem hanging up. (Forces &Q5, S36=4, and S48=7.)
\N3 Selects auto reliable mode. This operates the same as \N2 except failure to make
a reliable connection results in the modem falling back to the speed buffered
normal mode. (Forces &Q5, S36=7, and S48=7.)
\N4 Selects LAPM error-correction mode. Failure to make an LAPM error-correction
connection results in the modem hanging up. (Forces &Q5 and S48=0.) Note:
The -K1 command can override the \N4 command.
\N5 Selects MNP error-correction mode. Failure to make an MNP error-correction
connection results in the modem hanging up. (Forces &Q5, S36=4, and
S48=128.)

Result Code Meaning

OK n = 0 to 5
ERROR Otherwise

\Vn - Single Line Connect Message Enable

The single line connect message format can be enabled or disabled by the \Vn command as follows:

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Parameter Value Meaning

\V0 Connect messages are controlled by the command settings X, W, and S95.
\V1 Connect messages are displayed in the single line format described below subject
to the command settings V (Verbose) and Q (Quiet). In Non-Verbose mode (V0),
single line connect messages are disabled and a single numeric result code is
generated for CONNECT DTE.

When single line connect messages are enabled, there are no CARRIER, PROTOCOL, or
COMPRESSION messages apart from the fields described below.
The single line connect message format is:
CONNECT <DTE Speed></Modulation></Protocol></Compression></Line Speed>/<Voice and
Data>
where:
• DTE Speed = DTE speed, e.g., 57600.
• Modulation = “K56” for K56flex modulations,
“V32” for V.32 or V.32bis modulations,
“V34” for V.34 modulations.

Note Modulation parameter is omitted for all other modulations.

• Protocol = “NONE” for no protocol,

“ALT” for Microcom Network Protocol,
“LAPM” for LAP-M protocol.
• Compression = “CLASS5” for Microcom MNP5 compression,
“V42BIS” for V.42bis compression.

Note Compression parameter is omitted if protocol is NONE

• Line Speed
– Asymmetric rates are displayed as /rate:TX/rate:RX, e.g., /56000:TX/31200:RX for K56flex, or
/1200:TX/75:RX for V.23.
– Symmetric rates are displayed as a single DCE rate, e.g., 14400.
• Voice and Data = Blank for Data mode only.

AT+ Commands
A “+” command must be terminated by the semicolon “;” character (ASCII 3Bh) if in a command string
prior to another command, or by the <CR> at the end of the command string.

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+A8E – Enable/Disable V.8bis (K56flex) Operation

This command enables or disables K56flex operation by enabling or disabling V.8bis negotiation.

Syntax
+A8E = 0,0,00,<v8b>,0,0

Defined Values

Parameter Meaning Values

<v8b> Number which enables and 0: Disables V.8bis (K56flex) negotiation.
disables V.8bis (K56flex)
1: Enable V.8bis (K56flex) negotiation.
negotiation.
(Default.)

Reporting Current or Selected Values

Command +A8E?
Response +A8E: 0,0,00,1,0,0 (For the defaults)

Reporting Supported Range of Parameter Values

Command +A8E=?
Response +A8E: 0,0,00,(0-1),0,0

+MS - Select Modulation

This extended-format command selects the modulation, optionally enables or disables automode, and
optionally specifies the lowest and highest connection rates using one to four subparameters (client
modem) or five subparameters (server modem).

Syntax
+MS = <mod> [,[<automode>][,[<min_RX_rate>][,[<max_RX_rate>][,[<x_law>][,[<min_TX_rate>],
[[<max_TX_rate>]]]]]]]]<CR>

Note 1.For 14400 bps and lower speeds, the Nn command and S37 register can alternatively be used, in which
case the +MS subparameters will be modified to reflect the Nn and S37=x settings. Use of the Nn and
S37=x commands is not recommended but is provided for compatibility with existing communication
software. (S37 is not updated by the +MS command.)
2. Subparameters not entered (enter a comma only or <CR> to skip the last subparameter) remain at their
current values.

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Defined Values

Parameter Meaning Values

<mod> A decimal number which See “<mod> Command Information”
specifies the preferred section on page 50.
modulation (automode enabled),
or the modulation to use in
originating or answering a
connection (automode disabled).
<automode> An optional numeric value 0: Automode disabled
which enables or disables 1: Automode enabled using V.8bis/V.8 or
automatic modulation V.32 Annex A (Default)
negotiation using V.8 bis/V.8 or
V.32 bis Annex A. Note There are modulations for which
there is no automatic negotiation.
For example: Bell 212
(<mod> = 69).

For further information on automode, see

“<automode Command Information”
section on page 51.
<min_RX_rate> An optional decimal number 300 to 33600.
which specifies the lowest rate
Default is 300.
(bps) at which the modem may
receive data during a connection.
<max_RX_rate> An optional decimal number 300 to 33600.
which specifies the highest rate
Default is 33600.
(bps) at which the modem may
receive during a connection.
<x_law> An optional number which 0 = -Law
specifies the codec type and is
1 = A-Law
valid for the server modem only.
Any value entered for the client Note ATZ will reset the <x_law>
modem is ignored. selection to 0 ( -Law).
<min_TX_rate> An optional decimal number 300 to 56000.
which specifies the lowest rate Default is 300.
(bps) at which the modem may
transmit during a connection.
<max_TX_rate> An optional decimal number 300 to 56000.
which specifies the highest rate Default is 33600.
(bps) at which the modem may
transmit during a connection.

<mod> Command Information

<mod> Value Modulation Possible Rates (bps) 1

0 V.21 300

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<mod> Value Modulation Possible Rates (bps) 1

1 V.22 1200
2 V.22 bis 2400 or 1200
3 V.232 1200
9 V.32 9600 or 4800
10 V.32 bis 14400, 12000, 9600, 7200, or 4800
11 V.34 33600, 31200, 28800, 26400, 24000, 21600,
19200, 16800, 14400, 12000, 9600, 7200, 4800, or
2400
12 V.90 56000, 54667, 53333, 52000, 50667, 49333,
48000, 46667, 45333, 42667, 41333, 40000,
38667, 37333, 36000, 34667, 33333, 32000,
30667, 29333, 28000
56 K56flex 56000, 54000, 52000, 50000, 48000, 46000,
44000, 42000, 40000, 38000, 36000, 34000,
32000
64 Bell 103 300
69 Bell 212 1200
1. See optional <automode>, <min_RX_rate>, <max_RX_rate> and <max_TX_rate>subparameters.
2. For V.23, originating modes transmit at 75 bps and receive at 1200 bps; answering modes transmit at
1200 bps and receive at 75 bps. The rate is always specified as 1200 bps.

The modem may also automatically switch to another modulation (automode), subject to the following
constraints:
• The modem may not be able to automatically switch from the current modulation (specified by
<mod>) to some other modulation. For example, there is no standard way to automode from Bell
103 to V.23.
• The DTE may disable automode operation (see <automode> below).
• The DTE may constrain the range of modulations available by specifying the lowest and highest
rates (see <min_rate> and <max_rate> above).

<automode Command Information

For <automode> = 0 (automode disabled, i.e., fixed modulation):
• If <max_rate> is within the rates supported by the selected modulation, the selected rate is that
specified by <max_rate>. For example:
+MS=10,0,1200,4800 selects V.32 bis 4800 bps fixed rate.
• If <max_rate> is greater than the highest speed supported by the modulation specified by <mod>,
the starting rate is the highest rate supported by the selected modulation. For example:
+MS=10,0,2400,14400 selects V.32 bis 14400, 12000, 9600, 7200, or 4800 bps.
• To emulate issuance of the N0S37=x command sequence to select fixed mode operation, specify the
<max_rate> and <min_rate> both to be the same requested speed, and <mod> to be the modulation
for that speed. For example:
+MS=11,0,16800,16800 selects V.34 16800 bps fixed mode (no comparable S37 command).
+MS=10,0,12000,12000 selects V.32 bis 12000 bps fixed mode (same as N0S37=10).
For <automode> = 1 (automode enabled, i.e., automatically selected speed and modulation):

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 AT Commands Description

The modem connects at the highest possible rate in accordance with V.8 bis/V.8, or V.32 bis Annex A if
V.8 bis/V.8 is not supported by the remote modem.
• If <max_rate> is greater than the highest rate supported by the modulation specified by <mod>, the
modem automodes down from the highest rate of the selected modulation. For example:
+MS=10,1,1200,24000 selects automoding down from V.32 bis 14400 bps.
• To emulate issuance of the N1S37=x sequence command, specify the modulation and the rate to start
automoding down from using <mod> and <max_rate>, respectively. Set <min_rate> to 300 to allow
automoding all the way down to V.21 300 bps. For example:
+MS=11,1,300,16800 selects automode starting at V.34 16800 bps (no comparable S37 command).
+MS=9,1,300,12000 selects automode starting at V.32 bis 12000 bps (same as N1S37=10).

Reporting Selected Options

Command +MS?
Response +MS: <mod>,<automode>,<min_RX_rate>,
<max_RX_rate>,<x_law>,<min_TX_rate>,
<max_TX_rate>
Example +MS: 12,1,300,33600,0,300,56000 (for default values)

Reporting Supported Options

Command +MS=?
Response +MS: (list of supported <mod> values), (list of
supported <automode> values), (list of supported
<min_RX_rate> values), (list of supported
<max_RX_rate> values), (list of supported <x_law>
values), (list of supported <min_TX_rate> values),
(list of supported max_TX_rate> values)
Example +MS: (0,1,2,3,9,10,11,12,56,64,69), (0,1),
(300-33600), (300-336000), (0,1), (300-56000),
(300-56000)

+ISP Command - Select Digital Pass-Through Mode or Analog Modem Connection

The +ISP command selects digital pass-through mode or analog modem connection.

Syntax

Defined Values

Parameter Meaning Values

X Selects digital pass-through
mode or the analog modem
connection

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 AT Commands Description

The +ISP command operates as following:

+ISP=X X=0 Digital 64 kbps pass-through mode
X=1 Digital 56 kbps pass-through mode
X=2 Analog modem connection

+IPT Command – ISDN Protocol Selection

The +IPT command selects the ISDN protocol.

Syntax
+IPT = X

Defined Values

Parameter Meaning Values

X Selects ISDN protocol 0: Asynchronous pass-through mode
1: Synchronous pass-through mode. This
will make the channel an ISDN B channel
and transparently pass ISDN HDLC
frames.
2: V.120 rate adaption protocol multi-frame
mode (MuItiframe I mode).
3: V.120 rate adaption protocol ui-frame
mode (UI mode).
4: V.110 rate adaption protocol.

Note • AT+IPT configures V.120 to be either off (+IPT = 0, 1, or 4), UI mode (+IPT = 3), or MuItiframe I
mode (+IPT =2).
• Multiframe I mode operates similarly to V. 42, in that information frames are exchanged and frames
are resent when necessary.
• UI mode is unacknowledged.
• It is recommended that V.120 use Multiframe I mode whenever possible.
• There is no detection phase, signaling stack software is used to determine that V.120 is to be
negotiated.
• SABME-UA is exchanged to go into MuItiframe I mode. XIDS are exchanged to go into UI mode.

+IPR Command – Async Rate Selection

The +IPR command selects the async rate.

Syntax
+IPR = r

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 AT Commands Description

Defined Values

Parameter Meaning Values

r Selects the async rate 600, 1200, 2400, 4800, 7200, 9600,
12000, 14400, 19200, 24000, 28800, or
38400 bps

Example Command Sequence for V.110

1. 1) AT+ISP=0(Select 64 kbps pass-through mode)
2. 2) AT+IPT=4(Select V.110)
3. 3) AT+IPR= 19200(Select async 19200 bps rate)
4. 4) ATD or ATA(Command connect or answer)
V.110 will be automatically configured. The E1, E2, and E3 bits will be initialized based on Table
5/V.110, and the frames will be generated based on the adaption rates (Table 6a-f/V.110).

Disconnect:
+++ATH for both modems

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 V92 Data Mode AT Commands

V92 Data Mode AT Commands

V.92 Data mode is enabled or disabled using AT commands.

New Connect Message

With the addition of V.92 features, the CSM reports different connect messages as follows:
• In the one-line format, the modulation is reported as V92 when the modems have successfully
connected using the QuickConnect algorithm.
• V44 is reported for connections successfully negotiating V.44 compression.

AT Commands
The AT commands available for V.92 mode are listed below and described in more detail in the
subsequent sections. The &V2 Diagnostics available in V.92 mode are also described.
• +QC - V.92 QuickConnect Enable
• +HEN - Modem On-Hold Enable
• +HTL—Modem On-Hold Time-Out Setting
• +DS44—V.44 Compression Parameters
• +DCS—V.42bis/V.44 Negotiation Enable
• %C—Enable/Disable Data Compression Negotiation
• V.92 Specific Diagnostics

+QC - V.92 QuickConnect Enable

This command enables or disables the V.92 QuickConnect feature. V.92 QuickConnect allows for a fast
V.92 training sequence (about 10 seconds). If enabled, V.92 must also be supported by the client modem
for V.92 operation.

Syntax:
+QC = <QCE>,<Level of ANSPCM>;

Defined Values:

Parameter Meaning Values

<QCE> Number which enables and 0: Disables V.92 QuickConnect (Default)
disables V.92 QuickConnect.
1: Enables V.92 QuickConnect.
<Level of ANSPCM> Number which sets the level of 0: -9dBm0
the ANSPCM.
1: -12 dBm0 (Default)
2: -15 dBm0
3: -18 dBm0

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 V92 Data Mode AT Commands

Reporting Current or Selected Values:

Command +QC?
Response +QC: <QCE value>, <Level of ANSPCM>
Example +QC: 0,1 (for the defaults)

Reporting Supported Range of Parameter Values:

Command +QC=?
Response +QC: (<QCE> range), (<Level of ANSPCM> range)
Example +QC: (0,1), (0-3)

+HEN - Modem On-Hold Enable

This command enables or disables the Modem On-Hold feature.
Modem On-Hold allows the client modem to accept a Call Waiting call without releasing the current data
connection. When the client is finished with the voice call, the modems reconnect and continue where
the data connection was interrupted.
Even when disabled, the modem still responds to the remote’s MH sequences; the modem just does not
allow being put on-hold. When disabled and an MHreq is received, an MHnack is sent in return. The
remote then decides to either disconnect (by sending MHclrd) or request a fast reconnect (by sending
MHfrr). If the remote decides to disconnect, the server modem logs the disconnect as Remote Call
Waiting.

Syntax:
+HEN = <MHE>, <Max MH sessions>;

Defined Values:

Parameter Meaning Values

<MHE> Number which 0: Disables Modem On-Hold. Rejects
enables/disables the Modem any requests to be placed on-hold
On-Hold feature. (Default).
1: Enables Modem On-Hold. Allows
requests to be placed on-hold for the
amount of time specified by the +HTL
command.
<Max MH sessions> Decimal number which 0: No limit (Default).
indicates the maximum number
n: The value is the maximum number of
of MH sessions allowed. This
times the modem allows being placed
parameter is ignored when
on-hold.
<MHE> is 0.

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 V92 Data Mode AT Commands

Reporting Current or Selected Values:

Command +HEN?
Response +HEN: <MHE value>,< Max MH sessions >
Example +HEN: 0, 0 (For the defaults)

Reporting Supported Range of Parameter Values:

Command +HEN=?
Response +HEN: (<MHE> range), (<Max MH sessions> range)
Example +HEN: (0,1), (0–255)

+HTL—Modem On-Hold Time-Out Setting

This command allows the user to specify the desired maximum time-out for the MH feature.
Modem On-Hold allows the client modem to accept a Call Waiting call without releasing the current data
connection. When the client is finished with the voice call, the modems reconnect and continue where
the data connection was interrupted.
The +HTL value is transferred to the requesting modem in the MHack. If the remote does not send MHfrr
(request for fast reconnect) or MHclrd (request for cleardown) within the specified time, the modem
disconnects with a MH Time-Out disconnect reason. When this value is set to 13 (no limit), the Host can
disconnect the call by using ATH or by dropping DTR. The server modem records the disconnect with
a Local Request While On-Hold reason.

Syntax:
+HTL= <T1>;

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 V92 Data Mode AT Commands

Defined Values:

Parameter Meaning Values

<T1> Decimal number which sets the 0: Reserved
maximum time-out for the MH
1: 10 seconds
feature.
2: 20 seconds
3: 30 seconds
4: 40 seconds
5: 1 minute (Default)
6: 2 minutes
7: 3 minutes
8: 4 minutes
9: 6 minutes
10: 8 minutes
11: 12 minutes
12: 16 minutes
13: Time-out handled by Host
14: Reserved
15: Reserved

Reporting Current or Selected Values:

Command +HTL?
Response +HTL: <T1 value>
Example +HTL: 5 (For the defaults)

Reporting Supported Range of Parameter Values:

Command +HTL=?
Response +HTL: (T1 range)
Example +HTL: (0–15)

+DS44—V.44 Compression Parameters

This command is used to adjust the parameters for V.44 compression. V.44 is a feature that allows higher
compression rates with certain file types. This compression is optimized for internet traffic.
For more information, refer to ITU-T V.44.

Syntax:
+DS44 = <dir>, <comp neg>, <max code tx>, <max code rx>, <max string tx>, <max string rx>,
<max hist tx>, <max hist rx>

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 V92 Data Mode AT Commands

Defined Values:

Parameter Meaning Values

<dir> Number which sets desired 0: Negotiated. No compression.
direction of operation of the data
1: Transmit only.
compression.
2: Receive only.
3: Both directions. Accept any direction.
<comp neg> Number which specifies whether 0: Do not disconnect if Rec. V.44 is not
or not the DCS should continue negotiated by the remote DCE as
to operate if the desired result is specified in <direction>.
not obtained. 1: Disconnect if Rec. V.44 is not
negotiated by the remote DCE as
specified in <direction>.
< max code tx > Decimal number which specifies Range = 256–2048
the maximum number of
codewords which should be
negotiated in the transmit
direction.
< max code rx > Decimal number which specifies Range = 256–2048
the maximum number of
codewords which should be
negotiated in the transmit
direction.
< max string tx > Decimal number which specifies Range = 31–255
the maximum string length
which should be negotiated in
the transmit direction.
< max string rx > Decimal number which specifies Range = 31–255
the maximum string length
which should be negotiated in
the receive direction.
< max hist tx > Decimal number which specifies Value = 2 x the number of codewords.
the maximum size of history
buffer which should be
negotiated in the transmit
direction.
< max hist rx > Decimal number which specifies Value = 2 x the number of codewords.
the maximum size of history
buffer which should be
negotiated in the receive
direction.

Default values: +DS44: 3, 0, 2048, 2048, 140, 140, 10240, 10240

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 V92 Data Mode AT Commands

Reporting Current or Selected Values

Command +DS44?
Response +DS44: <dir>, <comp neg>, <max code tx>, <max code rx>, <max
string tx>, <max string rx>, <max hist tx>, <max hist rx>
Example +DS44: 3, 0, 2048, 2048, 140, 140, 10420, 10420 (For the defaults)

Reporting Supported Range of Parameter Values

Command +DS44=?
Response +DS44: (dir range), (comp neg range), (code tx
range), (code rx range), (string tx range),
(string rx range), (hist tx range), (hist rx range)
Example +DS44: (0–3), (0–1), (256–2,048), (256–2,048),
(31–255), (31–255), (512–10,240), (512–10,240)

+DCS—V.42bis/V.44 Negotiation Enable

This command enables and disables V.42bis and V.44 data compression negotiation. Also, see the %Cn
command.
V.44 is a feature that allows higher compression rates with certain file types. This compression is
optimized for Internet traffic. For more information, see ITU-T V.44.

Syntax
+DCS = <V.42bis enable>, <V.44 enable>

Defined Values

Parameter Values
<V.42bis enable> 0: Do not allow V.42bis data compression negotiation.
1: Allow V.42bis data compression negotiation. (Default)
<V.44 enable> 0: Do not allow V.44 data compression negotiation.
1: Allow V.44 data compression negotiation. (Default)

Note 1. A V.44 connection is enabled by default. This is NOT reflected in S41 (bits 0 and 1). Nevertheless,
selection of %C4 or %C5 will change S41 (bit 0, 1) accordingly. V.44 can be disabled by the +DCS
command or by setting %C0 to %C3.
2. Except as described in Note 1, the +DCS or %Cn command, whichever was received last, selects the
data compression negotiation method.

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 V92 Data Mode AT Commands

Reporting Current or Selected Values

Command +DCS?
Response +DCS: <V.42bis enable>, <V.44 enable>
Example +DCS: 1, 1 (For the defaults)

Reporting Supported Range of Parameter Values

Command +DCS=?
Response +DCS: (range of V.42bis enable), (range of V.44 enable)
Example +DCS: (0,1), (0,1)

%C—Enable/Disable Data Compression Negotiation

This command is used to enable or disable data compression negotiation. The modem can only perform
data compression on an error corrected link. The parameter value, if valid, is reflected in S41 bits 0 and
1. See also the +DCS command.

Commands:
%Cn: Refer to the Error Detection and Data Compression Commands section for details.

V.92 Specific Diagnostics

V.92 specific diagnostics information available during a V.92 connection as reported by the &V2 AT
command are listed in Table 19.

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 V92 Data Mode AT Commands

Table 19 &V2 Statistics Information for V.92 Connections

Field Code Field Name Bit(s) Field Description

se Remote V.92 Capability 0 Indicates whether or not the remote modem indicated V.92
capability during the INFO0 sequence.
0 = V.92 not supported
1 = V.92 supported
QuickConnect Attempted 1 Indicates whether QuickConnect was attempted.
0 = QC not attempted
1 = QC attempted
V.92 Fallback to V.90 2 Indicates if the modem tried a V.92 QuickConnect and fell back to
a V.90 connection.
0 = Fallback to V.90 from V.92 QuickConnect did not occur
1 = Fallback to V.90 from V.92 QuickConnect occurred
QuickConnect Connected 3 Indicates whether the call actually connected with QuickConnect
0 = QC not connected
1 = QC connected
Short Phase 2 Request from 5 Indicates if the remote modem requested a short Phase 2
Remote 0 = Remote modem did not request a short Phase 2
1 = Remote modem requested a short phase 2
ANSPCM Levels 6-7 See Table 20.
sf UQTS and QC Identifiers Reports parameter values transferred during V.92 QuickConnect
sg Number of MH Sessions Requested Reports the number of Modem On-Hold sessions requested by the
remote modem.
sh Number of MH Sessions Granted Reports the number of Modem On-Hold sessions granted.
si MH State 0 Indicates whether the modem is currently On-Hold.
0 = Not On-Hold
1 = On-Hold
MH FRR 1 Indicates whether the modem is currently in FRR (Fast Reconnect
from MH)
0 = Not in FRR
1 = In FRR
MH Limit 2 Indicates whether the modem has reached its Modem On-Hold
Limit.
0 = Limit not reached
1 = On-Hold limit reached
DIL Transmission 3 Indicates if the DIL was sent
0 = DIL was not sent
1 = DIL was sent

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 V92 Data Mode AT Commands

Table 19 &V2 Statistics Information for V.92 Connections

Field Code Field Name Bit(s) Field Description

qa V.92 Disconnect Reasons Reports the reason for the last disconnect.
0x1A = Remote Call Waiting
0x1B = Modem On-Hold Time-out
0x1C = Local Request while Modem On-Hold
0x1D = Local Request while FRR
qb V.92 Retrain Reason Reports the reason for the last retrain.
0x11 = Modem was On-Hold
0x12 = Modem was in FRR
0x13 = Modem has sent a MH message

Table 20 V.92 ANSPCM Levels (&V2 - se)

Bit 7 Bit 6 ANSPCM Level

0 0 –9 dB
1 0 –12 dB
0 1 –15 dB
1 1 –18 dB

The Host may have to monitor the MH status so that connection status can be reported correctly. For
example, the upper layer statistics should record a disconnection due to Call Waiting as a normal
disconnection.

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 Error Detection and Data Compression Commands

Error Detection and Data Compression Commands

AT% Commands

%C - Enable/Disable Data Compression

Enables or disables data compression negotiation. The modem can only perform data compression on an
error corrected link. The parameter value, if valid, is reflected in S41 bits 0 and 1.

Parameter Meaning
%C0 Disables data compression.
%C1 Enables MNP 5 data compression negotiation.
%C2 Enables V.42 bis data compression.
%C3 Enables both V.42 bis and MNP 5 data compression.
%C4 Forces V.44 data compression negotiation with fallback to no data compression.
%C5 Allows V.44 data compression negotiation and fallback to V.42 bis and MNP 5 data
compression negotiation the same as %C3 (Default).

Note • A V.44 connection is enabled by default. This is NOT reflected in S41 (bits 0 and 1). Nevertheless,
selection of %C4 or %C5 will change S41 (bit 0, 1) accordingly. V.44 can be disabled by the +DCS
command or by setting %C0 to %C3.
• Except as described in the previous paragraph, the +DCS or %Cn command, whichever was received last,
selects the data compression negotiation method.

Result Code Meaning

OK n = 0 to 5
ERROR Otherwise

AT\ Commands

\An - Select Maximum MNP Block Size

The modem will operate an MNP error corrected link using a maximum block size controlled by the
parameter supplied. The parameter value, if valid, is written to S40 bits 6 and 7.

Parameter Meaning
\A0 64 characters
\A1 128 characters (default)

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 Error Detection and Data Compression Commands

Parameter Meaning
\A2 192 characters
\A3 256 characters

Result Code Meaning

OK n = 0 to 3
ERROR Otherwise

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 MNP 10EC Commands

MNP 10EC Commands

AT-SEC Commands

-SEC=n - Enable/Disable MNP10-EC

Enables or disables MNP10-EC operation.

Syntax
-SEC=n,[<tx level>]

Defined Values:

Parameter Meaning Values

<tx level> Decimal number which is the 0: Disables MNP10-EC; the transmit level
optional transmit level is that defined in S91.
subparameter.
1, [<tx level]: Enables MPC10-EC with
the transmit level being defined by the
subparameter <tx level>.
Range is 0 to 30 (0 dBm to -30 dBm).
Default is unspecified in S91.

Result Code Meaning

OK n = 0, or 1 with <tx level> from 0 to 30
ERROR Otherwise

Example:
AT-SEC=1,18 enables MNP10-EC and sets the transmit level to -18 dBm.

Note If AT-SEC=0, the modem will automatically set AT-SEC=1 if the remote modem indicates Cellular in the V.8
bis/V.8 phase or if a Cellular Driver is loaded and the Cell Phone is attached.

Inquiries
AT-SEC? retrieves the current -SEC command settings, e.g., 1,18.

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 AT Command Result Codes

AT Command Result Codes

The modem responds to commands from the DTE and to activity on the line by signaling to the DTE in
the form of result codes. The result codes that the modem can send are described in Table 21.
Two forms of each result code are available: long-form, an English-like "verbose" response, and
short-form, a data-like numeric response (included in parentheses following the long-form). The
long-form code is preceded and terminated by the sequence < CR> < LF>. The short-form is terminated
by < CR>, only with no preceding sequence.
If result messages are suppressed, nothing is returned to the DTE. The long-form results codes can be
modified by the OEM through the ConfigurACE Configuration Utility Program. (See ConfigurACE
description.)

Table 21 AT Command Result Code Definitions

Code Message Meaning

+F4 +FCERROR High speed fax data (V.27, V.29, V.33, or V.17) is expected but a V.21
signal is received.
0 OK A command line has been executed.
1 CONNECT For X command values specifying no speed reporting, the modem has
connected to the line and either the line speed is 300 bps and line speed
is enabled, or the DTE speed is 300 bps and DTE speed reporting is
enabled.
2 RING An incoming ring signal is detected on the line. What qualifies as a ring
signal is determined by country-dependent parameters, modifiable
through ConfigurACE.
When cellular interface is selected, RING indicates that the cellular
phone is receiving an receiving an incoming call.
3 NO CARRIER Sent when attempting to establish a call if:
• Ringback is detected and later ceases but no carrier is detected
within the period of time determined by register S7, or
• No ringback is detected within the period of time determined by
register S7.
Also sent when the modem auto-disconnects due to loss of carrier.
For X0, sent for the following conditions:
• If busy tone detection is enforced, busy or circuit busy has been
detected.
• If dial tone detection is enforced or selected, dial tone has not been
detected.

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 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

4 ERROR Sent during an attempt to execute a command line if any of the following
conditions occur:
• The command line contains a syntax error.
• The modem cannot execute a command contained in the command
line, i.e., the command does not exist or is not supported.
• A command parameter within the command line is outside the
permitted range.
For X0, X1, X2, and X3, this message is sent instead of DELAYED and
BLACKLISTED.
5 CONNECT 1200 The modem has connected to the line and either the line speed is 1200
bps and DCE speed reporting is enabled, or the DTE speed is 1200 bps
and DTE speed reporting is enabled.
6 NO DIALTONE For X2 and X4, the modem has been instructed to wait for dial tone
during dialing but none is received.
When cellular phone interface is selected, indicates that cellular service
is not currently available.
7 BUSY For X3 and X4, if busy tone detection is enforced, the busy (engaged)
signal is detected on the line when the modem is attempting to originate
a call.
8 NO ANSWER The modem is attempting to originate a call if a continuous ringback
signal is detected on the line until the expiration of the timer S7.
9 CONNECT 0600 The modem has connected to the line, the DTE speed is 600 bps, and
DTE speed reporting is enabled.
10 CONNECT 2400 The modem has connected to the line and either the line speed is 2400
bps and DCE speed reporting is enabled, or the DTE speed is 2400 bps
and DTE speed reporting is enabled.
11 CONNECT 4800 The modem has connected to the line and either the line speed is 4800
bps and DCE speed reporting is enabled, or the DTE speed is 4800 bps
and DTE speed reporting is enabled.
12 CONNECT 9600 The modem has connected to the line and either the line speed is 9600
bps and DCE speed reporting is enabled, or the DTE speed is 9600 bps
and DTE speed reporting is enabled.
13 CONNECT 7200 The modem has connected to the line at 7200 bps and DCE speed
reporting is enabled.
14 CONNECT 12000 The modem has connected to the line at 12000 bps and DCE speed
reporting is enabled.
15 CONNECT 14400 The modem has connected to the line at 14400 bps and DCE speed
reporting is enabled.
16 CONNECT 19200 The modem has connected to the line and either the line speed is 19200
bps and DCE speed reporting is enabled, or the DTE speed is 19200 bps
and DTE speed reporting is enabled.

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 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

17 CONNECT 38400 The modem has connected to the line, the DTE speed is 38400 bps, and
DTE speed reporting is enabled.
18 CONNECT 57600 The modem has connected to the line, the DTE speed is 57600 bps, and
DTE speed reporting is enabled.
19 CONNECT 115200 The modem has connected to the line, the DTE speed is 115200 bps, and
DTE speed reporting is enabled.
22 CONNECT The modem has established a V.23 originate connection and line speed
75TX/1200RX reporting is enabled.
23 CONNECT The modem has established a V.23 answer connection and line speed
1200TX/75RX reporting is enabled.
24 DELAYED For X4, sent when a call fails to connect and the number dialed is
considered 'delayed' due to country blacklisting requirements.
32 BLACKLISTED For X4, sent when a call fails to connect and the number dialed is
considered 'blacklisted'.
33 FAX A fax modem connection is established in a facsimile mode.
35 DATA A data modem connection is established in a facsimile mode.
40 CARRIER 300 The modem has connected to the line at 0-300 bps and carrier reporting
is enabled. (See S95 and Xn.)
44 CARRIER 1200/75 The V.23 backward channel carrier is detected and carrier reporting is
enabled. (See S95 and Xn.)
45 CARRIER 75/1200 The V.23 forward channel carrier is detected and carrier reporting is
enabled. (See S95 and Xn.)
46 CARRIER 1200 The modem has connected to the line at 1200 bps and carrier reporting
is enabled. (See S95 and Xn.)
47 CARRIER 2400 The modem has connected to the line at 2400 bps and carrier reporting
is enabled. (See S95 and Xn.)
48 CARRIER 4800 The modem has connected to the line at 4800 bps and carrier reporting
is enabled. (See S95 and Xn.)
49 CARRIER 7200 The modem has connected to the line at 7200 bps and carrier reporting
is enabled. (See S95 and Xn.)
50 CARRIER 9600 The modem has connected to the line at 9600 bps and carrier reporting
is enabled. (See S95 and Xn.)
51 CARRIER 12000 The modem has connected to the line at 12000 bps and carrier reporting
is enabled. (See S95 and Xn.)
52 CARRIER 14400 The modem has connected to the line at 14400 bps and carrier reporting
is enabled. (See S95 and Xn.)
53 CARRIER 16800 The modem has connected to the line at 16800 bps and carrier reporting
is enabled. (See S95 and Xn.)
54 CARRIER 19200 The modem has connected to the line at 19200 bps and carrier reporting
is enabled. (See S95 and Xn.)
55 CARRIER 21600 The modem has connected to the line at 21600 bps and carrier reporting
is enabled. (See S95 and Xn.)

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69
 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

56 CARRIER 24000 The modem has connected to the line at 24000 bps and carrier reporting
is enabled. (See S95 and Xn.)
57 CARRIER 26400 The modem has connected to the line at 26400 bps and carrier reporting
is enabled. (See S95 and Xn.)
58 CARRIER 28800 The modem has connected to the line at 28800 bps and carrier reporting
is enabled. (See S95 and Xn.)
59 CONNECT 16800 The modem has connected to the line, the DTE speed is 16800 bps and
DTE speed reporting is enabled.
61 CONNECT 21600 The modem has connected to the line, the DTE speed is 21600 bps and
DTE speed reporting is enabled.
62 CONNECT 24000 The modem has connected to the line, the DTE speed is 24000 bps and
DTE speed reporting is enabled.
63 CONNECT 26400 The modem has connected to the line, the DTE speed is 26400 bps and
DTE speed reporting is enabled.
64 CONNECT 28800 The modem has connected to the line and either the line speed is 28800
bps and DCE speed reporting is enabled, or the DTE speed is 28800 bps
and DTE speed reporting is enabled.
66 COMPRESSION: The modem has connected to the line in MNP Class 5 and
CLASS 5 COMPRESSION message reporting is enabled. (See S95, Wn, and Xn.)
67 COMPRESSION: The modem has connected to the line in V.42 bis and COMPRESSION
V.42 bis message reporting is enabled. (See S95, Wn, and Xn.)
69 COMPRESSION: The modem has connected to the line without data compression and
NONE COMPRESSION message reporting is enabled. (See S95, Wn, and Xn.)
70 PROTOCOL: The modem has connected to the line without any form of error
NONE correction and the PROTOCOL message reporting has been enabled.
(See S95, Wn, and Xn.)
77 PROTOCOL: The modem has connected to the line in V.42 LAPM error correction
LAPM mode and PROTOCOL message reporting has been enabled. (See S95,
Wn, and Xn.)
78 CARRIER 31200 The modem has connected to the line at 31200 bps and carrier reporting
is enabled. (See S95 and Xn.)
79 CARRIER 33600 The modem has connected to the line at 33600 bps and carrier reporting
is enabled. (See S95 and Xn.)
80 PROTOCOL: ALT Sent when the modem has connected in the MNP mode of error
correction, and PROTOCOL message reporting has been enabled. (See
S95, Wn, and Xn.)
81 PROTOCOL: The modem has connected in the MNP 10 mode and cellular power level
ALT-CELLULAR adjustment is enabled (")M1 or )M2"). (See S95, Wn, and Xn.)
83 LINE IN USE The modem attempted to go off-hook when an extension was already
occupying the line.
84 CONNECT 33600 The modem has connected to the line, the DTE speed is 33600 bps and
the DTE speed reporting is enabled.

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70
 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

91 CONNECT 31200 The modem has connected to the line DTE speed is 31200 bps and the
modem is to report the DTE speed upon connecting.
150 CARRIER 32000 The modem has connected to the line at 32000 bps and carrier reporting
is enabled. (See S95 and Xn.)
151 CARRIER 34000 The modem has connected to the line at 34000 bps and carrier reporting
is enabled. (See S95 and Xn.)
152 CARRIER 36000 The modem has connected to the line at 36000 bps and carrier reporting
is enabled. (See S95 and Xn.)
153 CARRIER 38000 The modem has connected to the line at 38000 bps and carrier reporting
is enabled. (See S95 and Xn.)
154 CARRIER 40000 The modem has connected to the line at 40000 bps and carrier reporting
is enabled. (See S95 and Xn.)
155 CARRIER 42000 The modem has connected to the line at 42000 bps and carrier reporting
is enabled. (See S95 and Xn.)
156 CARRIER 44000 The modem has connected to the line at 44000 bps and carrier reporting
is enabled. (See S95 and Xn.)
157 CARRIER 46000 The modem has connected to the line at 46000 bps and carrier reporting
is enabled. (See S95 and Xn.)
158 CARRIER 48000 The modem has connected to the line at 48000 bps and carrier reporting
is enabled. (See S95 and Xn.)
159 CARRIER 50000 The modem has connected to the line at 50000 bps and carrier reporting
is enabled. (See S95 and Xn.)
160 CARRIER 52000 The modem has connected to the line at 52000 bps and carrier reporting
is enabled. (See S95 and Xn.)
161 CARRIER 54000 The modem has connected to the line at 54000 bps and carrier reporting
is enabled. (See S95 and Xn.)
162 CARRIER 56000 The modem has connected to the line at 56000 bps and carrier reporting
is enabled. (See S95 and Xn.)
165 CONNECT 32000 The modem has connected to the line at 32000 bps and DCE speed
reporting is enabled.
166 CONNECT 34000 The modem has connected to the line at 34000 bps and DCE speed
reporting is enabled.
167 CONNECT 36000 The modem has connected to the line at 36000 bps and DCE speed
reporting is enabled.
168 CONNECT 38000 The modem has connected to the line at 38000 bps and DCE speed
reporting is enabled.
169 CONNECT 40000 The modem has connected to the line at 40000 bps and DCE speed
reporting is enabled.
170 CONNECT 42000 The modem has connected to the line at 42000 bps and DCE speed
reporting is enabled.
171 CONNECT 44000 The modem has connected to the line at 44000 bps and DCE speed
reporting is enabled.

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71
 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

172 CONNECT 46000 The modem has connected to the line at 46000 bps and DCE speed
reporting is enabled.
173 CONNECT 48000 The modem has connected to the line at 48000 bps and DCE speed
reporting is enabled.
174 CONNECT 50000 The modem has connected to the line at 50000 bps and DCE speed
reporting is enabled.
175 CONNECT 52000 The modem has connected to the line at 52000 bps and DCE speed
reporting is enabled.
176 CONNECT 54000 The modem has connected to the line at 54000 bps and DCE speed
reporting is enabled.
177 CONNECT 56000 The modem has connected to the line at 56000 bps and DCE speed
reporting is enabled.
178 CONNECT 230400 The modem has connected to the line, the DTE speed is 230400 bps, and
DTE speed reporting is enabled.
180 CONNECT 28000 The modem has connected to the line at 28000 bps and DCE speed
reporting is enabled.
181 CONNECT 29333 The modem has connected to the line at 29333 bps and DCE speed
reporting is enabled.
182 CONNECT 30667 The modem has connected to the line at 30667 bps and DCE speed
reporting is enabled.
183 CONNECT 33333 The modem has connected to the line at 33333 bps and DCE speed
reporting is enabled.
184 CONNECT 34667 The modem has connected to the line at 34667 bps and DCE speed
reporting is enabled.
185 CONNECT 37333 The modem has connected to the line at 37333 bps and DCE speed
reporting is enabled.
186 CONNECT 38667 The modem has connected to the line at 38667 bps and DCE speed
reporting is enabled.
187 CONNECT 41333 The modem has connected to the line at 41333 bps and DCE speed
reporting is enabled.
188 CONNECT 42667 The modem has connected to the line at 42667 bps and DCE speed
reporting is enabled.
189 CONNECT 45333 The modem has connected to the line at 45333 bps and DCE speed
reporting is enabled.
190 CONNECT 46667 The modem has connected to the line at 46667 bps and DCE speed
reporting is enabled.
191 CONNECT 49333 The modem has connected to the line at 49333 bps and DCE speed
reporting is enabled.
192 CONNECT 50667 The modem has connected to the line at 50667 bps and DCE speed
reporting is enabled.
193 CONNECT 53333 The modem has connected to the line at 53333 bps and DCE speed
reporting is enabled.

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 AT Command Result Codes

Table 21 AT Command Result Code Definitions (continued)

Code Message Meaning

194 CONNECT 54667 The modem has connected to the line at 54667 bps and DCE speed
reporting is enabled.
195 CARRIER 28000 The modem has connected to the line at 28000 bps and carrier reporting
is enabled. (See S95 and Xn.)
196 CARRIER 29333 The modem has connected to the line at 29333 bps and carrier reporting
is enabled. (See S95 and Xn.)
197 CARRIER 30667 The modem has connected to the line at 30667 bps and carrier reporting
is enabled. (See S95 and Xn.)
198 CARRIER 33333 The modem has connected to the line at 33333 bps and carrier reporting
is enabled. (See S95 and Xn.)
199 CARRIER 34667 The modem has connected to the line at 34667 bps and carrier reporting
is enabled. (See S95 and Xn.)
200 CARRIER 37333 The modem has connected to the line at 37333 bps and carrier reporting
is enabled. (See S95 and Xn.)
201 CARRIER 38667 The modem has connected to the line at 38667 bps and carrier reporting
is enabled. (See S95 and Xn.)
202 CARRIER 41333 The modem has connected to the line at 41333 bps and carrier reporting
is enabled. (See S95 and Xn.)
203 CARRIER 42667 The modem has connected to the line at 42667 bps and carrier reporting
is enabled. (See S95 and Xn.)
204 CARRIER 45333 The modem has connected to the line at 45333 bps and carrier reporting
is enabled. (See S95 and Xn.)
205 CARRIER 46667 The modem has connected to the line at 46667 bps and carrier reporting
is enabled. (See S95 and Xn.)
206 CARRIER 49333 The modem has connected to the line at 49333 bps and carrier reporting
is enabled. (See S95 and Xn.)
207 CARRIER 50667 The modem has connected to the line at 50667 bps and carrier reporting
is enabled. (See S95 and Xn.)
208 CARRIER 53333 The modem has connected to the line at 53333 bps and carrier reporting
is enabled. (See S95 and Xn.)
209 CARRIER 54667 The modem has connected to the line at 54667 bps and carrier reporting
is enabled. (See S95 and Xn.)
Note 1. See \Vn for Result code selection, i.e., short form (result code) or verbose/extended (result
message).
2. See Wn for extended connect message control.
3. See S95 for extended result code enabling options (which override some Wn commands).
4. See Xn for extended result code subset enabling options.

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 S Registers

S Registers

S Register Summary
The S-Registers are summarized in this section along with their default values. Registers or register
fields quoted as “reserved” are reserved for current or future use by the firmware, or are permanently
overridden by PTT limitations.
The factory default values may be loaded at any time by entering the &Fn command.
Table 22 provides a summary of the S-Registers. The S Register Definitions section describes each
register in more detail.

Table 22 S Register Summary

Register Function Range Units Default

S0 Rings to Auto-Answer 0-255 rings 0
S1 Ring Counter 0-255 rings 0
S2 Escape Character 0-255 ASCII 43
S3 Carriage Return Character 0-127 ASCII 13
S4 Line Feed Character 0-127 ASCII 10
S5 Backspace Character 0-255 ASCII 8
S6 Wait Time for Dial Tone 2-255 s 2
S7 Wait Time for Carrier 1-255 s 60
S8 Reserved - - -
S9 Carrier Detect Response Time 1-255 0.1 s 6
S10 Carrier Loss Disconnect Time 1-255 0.1 s 14
S11 Reserved 50-255 0.001 s 95
S12 Escape Prompt Delay 0-255 0.02 s 50
S13 Reserved - - -
S14 General Bit Mapped Options Status - - 138 (8Ah)
S15 Reserved - - -
S16 Test Mode Bit Mapped Options - - 0
Status (&T)
S17 Reserved - - -
S18 Test Timer 0-255 s 0
S19 Reserved - - 0
S20 Reserved - - 0
S21 V.24/General Bit Mapped Options - - 52 (34h)
Status
S22 Speaker/Results Bit Mapped Options - - 119 (77h)
Status
S23 General Bit Mapped Options Status - 54 (36h)

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74
 S Registers

Table 22 S Register Summary (continued)

Register Function Range Units Default

S24 Sleep Inactivity Timer 0-255 s 09 (09h)
S25 Delay to DTR Off 0-255 s or 0.01 s 0
S26 RTS-to-CTS Delay 0-255 0.01 s 0
S27 General Bit Mapped Options Status - - 0
S28 General Bit-Mapped Options Status - - 6 (06h)
S29 Flash Dial Modifier Time 0-255 10 ms 17 (11h)
S30 Disconnect Inactivity Timer 0-255 10 s 19 (13h)
S31 General Bit-Mapped Options Status - - 1
S32 XON Character 0-255 ASCII -
S33 XOFF Character 0-255 ASCII 7
S34 V44 Compression 0-1 ASCII 0
S35 Reserved - - 20
S36 LAPM Failure Control - - 3
S37 Line Connection Speed - - 88 (58h)
S38 Delay Before Forced Hangup 0-255 s 139 (8Bh)
S39 Flow Control Bit Mapped Options - - -
Status
S40 General Bit-Mapped Options Status - - 7
S41 General Bit-Mapped Options Status - - 128(40h)
S42-S46 Reserved - - -
S48 V.42 Negotiation Control - - 13 (Country
dependent)
S82 LAPM Break Control - - 10 (Country
dependent)
S86 Call Failure Reason Code 0-255 - 47
S91 PSTN Transmit Attenuation Level in 0-15 dBm 223
Analog Modulations
S92 Fax Transmit Attenuation Level 0-15 dBm 255
S95 Result Code Messages Control - - 2
S200 Disable K56Plus Protocol - - 255
S201 Reserved 13
S202 K56flex/V90 Tx level & auto status 0-255 11
message
S204 Reserved 50
S210 Symbol Rate Limit 0-255 0
S220 Duration of Answer Tone 0-255 450 ms -12db
S221 Duration of Billing Delay 0-255 500 ms 0

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75
 S Registers

Table 22 S Register Summary (continued)

Register Function Range Units Default

S222 General purpose 0-255 - 09 (09h)
S223 V.90 Transmit level 11-31 Db 0
S224 Digital detect timer 0-100 Ms 0

S Register Definitions

S0 - Number of Rings to Auto-Answer

Sets the number of the rings required before the modem automatically answers a call. Setting this register
to zero disables auto-answer mode.

Range
0-255 rings

Default
0

S1 - Ring Counter
S1 is incremented each time the modem detects a ring signal on the telephone line. S1 is cleared if no
rings occur over an eight second interval.

Range
0-255 rings

Default
0

S2 - Escape Character
S2 holds the decimal value of the ASCII character used as the escape character. The default value
corresponds to an ASCII '+'. A value over 127 disables the escape process, i.e., no escape character will
be recognized.

Range
0-255, ASCII decimal

Default
43 (+)

S3 - Carriage Return Character

Sets the command line and result code terminator character. Pertains to asynchronous operation only.

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 S Registers

Range
0-127, ASCII decimal

Default
13 (Carriage Return)

S4 - Line Feed Character

Sets the character recognized as a line feed. Pertains to asynchronous operation only. The Line Feed
control character is output after the Carriage Return control character if verbose result codes are used.

Range
0-127, ASCII decimal

Default
10 (Line Feed)

S5 - Backspace Character
Sets the character recognized as a backspace. Pertains to asynchronous operation only. The modem will
not recognize the Backspace character if it is set to a value that is greater than 32 ASCII. This character
can be used to edit a command line. When the echo command is enabled, the modem echoes back to the
local DTE the Backspace character, an ASCII space character and a second Backspace character; this
means a total of three characters are transmitted each time the modem processes the Backspace character.

Range
0-32, ASCII decimal

Default
8 (Backspace)

S6 - Wait Time for Dial Tone Before Blind Dialing

Sets the length of time, in seconds, that the modem will wait before starting to dial after going off-hook
when blind dialing. This operation, however, may be affected by some ATX options according to country
restrictions. The “Wait for Dial Tone” call progress feature (W dial modifier in the dial string) will
override the value in register S6.
The modem always pauses for a minimum of 2 seconds, even if the value of S6 is less than 2 seconds.

Range
2-255 seconds

Default
2

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 S Registers

S7 - Wait Time for Carrier After Dial, for Silence, or for Dial Tone After “W” Dial Modifier
1. Sets the length of time, in seconds, that the modem will wait for carrier before hanging up. The timer
is started when the modem finishes dialing (originate), or 2 seconds after going off-hook (answer).
In originate mode, the timer is reset upon detection of answer tone if allowed by country restrictions.
2. Sets the length of time, in seconds, that modem will wait for silence when encountering the @ dial
modifier before continuing with the next dial string parameter.
3. Sets the length of time, in seconds, that the modem will wait for dial tone when encountering a “W”
dial modifier before continuing with the next dial string parameter.

Range
1-255 seconds

Default
50

S8 - Reserved

S9 - Carrier Detect Response Time

Sets the length of time, in tenths of a second, that the carrier must be present before the modem considers
it valid and turns on RLSD. As this time is increased, there is less chance to detect a false carrier due to
noise from the telephone line.

Range
1-255 tenths of a second

Default
6 (0.6 second)

S10 - Lost Carrier To Hang Up Delay

Sets the length of time, in tenths of a second, that the modem waits before hanging up after a loss of
carrier. This allows for a temporary carrier loss without causing the local modem to disconnect. When
register S10 is set to 255, the modem functions as if a carrier is always present.
The actual interval the modem waits before disconnecting is the value in register S10 minus the value in
register S9. Therefore, the S10 value must be greater than the S9 value or else the modem disconnects
before it recognizes the carrier.

Range
1-255 tenths of a second

Default
14 (1.4 seconds)

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 S Registers

S11 - DTMF Tone Duration

Returns OK. The default value is set to 95D. This register is reserved.

S12 - Escape Prompt Delay (EPD)

Returns OK.

Range
0-255

Default
50D

S13 - Reserved

S14 - General Bit Mapped Options Status

Indicates the status of command options.

Bit Meaning Values

0 This bit is ignored.
1 Command echo (En) 0: Disabled (E0)
1: Enabled (E1) (Default)
2 Quiet mode (Qn) 0: Send result codes (Q0) (Default)
1: Do not send result codes (Q1)
3 Result codes (Vn) 0: Numeric (V0)
1: Verbose (V1) (Default)
4 Reserved
5 Tone (T)/Pulse (P) 0: Tone (T) (Default)
1: Pulse (P)
6 Reserved
7 Originate/Answer 0: Answer
(This Bit is not used.)
1: Originate (Default)

Default
138 (8A hex) (10001010 binary)

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 S Registers

S15 - Reserved

S16 - General Bit Mapped Test Options Status

Indicates the test in progress status.

Bit Meaning Values

0 Local analog loopback (LAL) 0: Disabled (Default)
1: Enabled (&T1)
1 Not used
2 Local digital loopback 0: Disabled (Default)
1: Enabled (&T3)
3 Remote digital loopback (RDL) 0: Modem not in RDL (Default)
status
1: RDL in progress
4 RDL requested (AT&T6) 0: RDL not requested (Default)
1: RDL requested (&T6)
5 RDL with self test 0: Disabled (Default)
1: Enabled (&T7)
6 LAL with self test 0: Disabled (Default)
1: Enabled (&T8)
7 Not used

Default
0

S17 - Reserved

S18 - Test Timer

Sets the length of time, in seconds, that the modem conducts a test (commanded by &Tn) before
returning to the command mode. If this register value is zero, the test will not automatically terminate;
the test must be terminated from the command mode by issuing an &T0 or H command. When S18 is
non-zero, the modem returns the OK message upon test termination.

Range
0-255 seconds

Default
0

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 S Registers

S19 - Reserved

S20 - Reserved

S21 - V.24/General Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0 Set by &Jn command but ignored 0: &J0 (Default)
otherwise.
1: &J1
1 Reserved
2 CTS behavior (&Rn) 0: CTS tracks RTS (&R0)
1: CTS always on (&R1) (Default)
3-4 DTR behavior (&Dn) 0: &D0 selected
1: &D1 selected
2: &D2 selected (Default)
3: &D3 selected
5 RLSD (DCD) behavior (&Cn) 0: &C0 selected
1: &C1 selected (Default)
6 DSR behavior (&Sn) 0: &S0 selected (Default)
1: &S1 selected
7 Long space disconnect (Yn) 0: Y0 selected (Default)
1: Y1 selected

Default
52 (34h) (00110100b)

S22 - Speaker/Results Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0-1 Speaker volume (Ln) Not supported
2-3 Speaker control (Mn) Not supported
4-6 Limit result codes (Xn) Not supported
7 Reserved

Default
119 (77h) (01110111b)

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 S Registers

S23 - General Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0 Grant RDL 0: RDL not allowed (&T5) (Deafault)
1: RDL allowed (&T4)
1-5 Reserved
6-7 Guard tone (&Gn) 0: None (G0) (Default)
1: None (&G1)
2: 1800 Hz (&G2)

Default
54 (36h) (00111110b)

S24 - Sleep Inactivity Timer

Sets the length of time, in seconds, that the modem will operate in normal mode with no detected
telephone line or DTE line activity before entering low-power sleep mode. The timer is reset upon any
DTE line or telephone line activity. If the S24 value is zero, neither DTE line nor telephone inactivity
will cause the modem to enter the sleep mode.

Range
0-255 seconds

Default
0

S25 - Delay To DTR

Sets the length of time that the modem will ignore DTR for taking the action specified by &Dn. Its units
are seconds for synchronous modes and one hundredths of a second for other modes.

Range
0-255 (1 second for synchronous modes 1; 0.01 second otherwise)

Default
5

S26 - RTS to CTS Delay

Sets the time delay, in hundredths of a second, before the modem turns CTS ON after detecting an
OFF-to-ON transition on RTS when &R0 is commanded. Pertains to synchronous operation only.

Range
0-255 hundredths of a second

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 S Registers

Default
1

S27 - Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0, 1, 3 Synchronous/asynchronous See Sync/Async Bit Table.
selection (&Mn/&Qn)
2 Leased line control (&Ln) 0: Dial up line (&L0) (Default)
4-5 Internal clock set (Xn) 0:
1:
2:
6 CCITT/Bell mode select (Bn) 0: CCITT mode (B0)
1: Bell mode (B1) (Default)
7 Reserved

Table 23 Sync/Async Bit Table

Bit 3 Bit 1 Bit 0 Meaning

0 0 0 &M0 or &Q0
0 0 1 &M1 or &Q1
0 1 0 &M2 or &Q2
0 1 1 &M3 or &Q3
1 0 0 &Q4
1 0 1 &Q5 (Default)&Q6
1 1 0

Default
73 (49h) (01001001b)

S28 - Bit Mapped Options Status

Bit(s) Meaning Values

0-1 Reserved
2 Reserved Always 0

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 S Registers

Bit(s) Meaning Values

3-4 Pulse dialing (&Pn) 0: 39%-61% make/break ratio at 10 pulses per second (&P0) (Default)
1: 33%-67% make/break ratio at 10 pulses per second (&P1)
2: 39%-61% make/break ratio at 20 pulses per second (&P2)
3: 33%-67% make/break ratio at 20 pulses per second (&P3)
5-7 Reserved

Default
0

S29 - Flash Dial Modifier Time

Sets the length of time, in units of 10 ms, that the modem will go on-hook when it encounters the flash
(!) dial modifier in the dial string. The time can be limited as it is a country dependent parameter.

Range
0-255 10 ms intervals

Default
0 (0 ms)

S30 - Disconnect Inactivity Timer

Sets the length of time, in tens of seconds, that the modem will stay online before disconnecting when
no data is sent or received. In error-correction mode, any data transmitted or received will reset the timer.
In other modes, any data transmitted will reset the timer. The timer is inoperative in synchronous mode.

Range
0-255 tens of seconds (0-2550 seconds)

Default
0 (disabled)

S31 - Bit Mapped Options Status

Bit(s) Meaning Values

0 Single line connect message 0: Messages controlled by S95, Wn and Vn (\V0)
enable/disable (\Vn) (Default)
1: Single line connect message (\V1)
1 Auto line speed detection (Nn) 0: Disabled (N0)
1: Enabled (N1) (Default)

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 S Registers

Bit(s) Meaning Values

2-3 Error correction progress 0: DTE speed only (W0)
messages (Wn)
1: Full reporting (W1) (Default)
2: DCE speed only (W2)
4-5 Reserved
6-7 Reserved Default = 00b

Default
06 (06h) (00000110b)

S32 - XON Character

Sets the value of the XON character.

Range
0-255, ASCII decimal

Default
17 (11h)

S33 - XOFF Character

Sets the value of the XOFF character.

Range
0-255, ASCII decimal

Default
19 (13h)

S34 – V.44 compression

0 – disable
1 – Enable (default)

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 S Registers

S35 - Reserved

S36 - LAPM Failure Control

Bits Meaning Values

0-2 This value indicates what should 0: Modem disconnects.
happen upon a LAPM failure. 1: Modem stays on-line and a Direct mode
These fallback options are connection is established.
initiated immediately upon
connection if S48=128. If an 2: Reserved
invalid number is entered, the 3: Modem stays on-line and a Normal mode
number is accepted into the connection is established.
register, but S36 will act as if the
default value has been entered. 4: An MNP connection is attempted and if it fails,
the modem disconnects.
5: An MNP connection is attempted and if it fails, a
Direct mode connection is established.
6: Reserved
7: An MNP connection is attempted and if it fails, a
Normal mode connection is established. (Default)
3-7 Reserved

Default
7 (00000111b)

S37 - Desired Line Connection Speed

This register specifies the desired line connection speed.

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 S Registers

Bits Meaning Values

0-4 Desired line connection speed. If 0: Attempt automode connection. If N0 is active,
an invalid number is entered, the connection is attempted at the most recently sensed
number is accepted into the DTE speed (+MS command settings are updated to
register, but S37 will act as if the the appropriate values). If N1 is active, connection is
default value has been entered. attempted at the highest possible speed (e.g., +MS
settings are updated to 11,1,300,33600 to reflect
V.34, automode, 300 bps minimum speed, and
33600 bps maximum speed). (Default)
1-3: Attempt to connect at 300 bps.
4: Reserved
5: Attempt to connect at V.22 1200 bps.
6: Attempt to connect at V.22 2400 bps.
7: Attempt to connect at V.23.
8: Attempt to connect at V.32 bis/V.32 4800 bps.
9: Attempt to connect at V.32 bis/V.32 9600 bps.
10: Attempt to connect at V.32 bis 12000 bps.
11: Attempt to connect at V.32 bis 14400 bps.
12: Attempt to connect at V.32 bis 7200 bps.
5-7 Reserved

Default
0

Note • When the Nn command is issued or the S37 register value is modified, the +MS command
subparameters are updated to reflect the speed and modulation specified by the S37 value (see +MS
command). For example:
– If N0 command is active, S37=10 updates the +MS command subparameters to reflect
+MS=10,1,300,12000
– If N1 command is active, S37=10 updates the +MS command subparameters to reflect
+MS=10,0,12000,12000
• S37 is not updated by the +MS command.
• Use of the +MS command is recommended instead of the Nn and S37=x commands. Nn and S37=x
commands are supported for compatibility with existing communication software.

S38 - Delay Before Forced Hang Up

This register specifies the delay between the modem's receipt of the H command to disconnect (or
ON-to-OFF transition of DTR if the modem is programmed to follow the signal), and the disconnect
operation. Applicable to error-correction connection only. This register can be used to ensure that data
in the modem buffer is sent before the modem disconnects.

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Range
0-255 seconds

Default
20

Note • If S38 is set to a value between 0 and 254, the modem will wait that number of seconds for the
remote modem to acknowledge all data in the modem buffer before disconnecting. If time expires
before all data is sent, the NO CARRIER result code will be issued to indicate that data has been
lost. If all data is transmitted prior to time-out, the response to the H0 command will be OK.
• If S38 is set to 255, the modem does not time-out and continues to attempt to deliver data in the
buffer until the connection is lost or the data is delivered.

S39 - Flow Control Bit Mapped Options Status

Bits (s)Meaning Values

0-2 Status of command options 0: No flow control
3: RTS/CTS (&K3) (Default)
4: XON/XOFF (&K4)
5: Transparent XON (&K5)
6: Both methods (&K6)
3-7 Reserved

Default
3 (00000011b)

S40 - General Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0-1 MNP extended services (-Kn) 0: Disable extended services (-K0) (Default)
1: Enable extended services (-K1)
2: Enable extended services (-K2)
2 Reserved

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 S Registers

Bit(s) Meaning Values

3-5 Break handling (\Kn) 0: Not supported
1: Not supported
2: Not supported
3: \K5 default
4: Not supported
5: Not supported
6-7 MNP block size (\An) 0: 64 chars (\A0)
1: 128 chars (\A1) (Default)
2: 192 chars (\A2)
3: 256 chars (\A3)

Default
88 (58h) (01011000b)

S41 - General Bit Mapped Options Status

Indicates the status of command options.

Bit(s) Meaning Values

0-1 Compression negotiation 0: Disabled (%C0 or %C4)
selection (%Cn)
1: MNP 5 (%C1)
2: V.42 bis (%C2)
3: MNP 5 and V.42 bis (%C3 or %C5) (Default)
2-3 Auto retrain and fallback/fall 0: Retrain and fallback/fall forward disabled (%E0)
forward (%En)
1: Retrain enabled (%E1)
2: Fallback/fall forward enabled (%E2) (Default)
4-7 Reserved

Default
139 (8Bh) (10001011b)

S48 - V.42 Negotiation Action

The V.42 negotiation process determines the capabilities of the remote modem. However, when the
capabilities of the remote modem are known and negotiation is unnecessary, this process can be bypassed
if so desired.

Range
0, 7, or 128 If an invalid number is entered, it is accepted into the S-Register, but S48 will act as if 128
has been entered.

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 S Registers

Default
7

Register Value Meaning

S48 = 0 Disable negotiation; bypass the detection and negotiation phases; and proceed
with LAPM.
S48 = 7 Enable negotiation. (Default)
S48 = 128 Disable negotiation; bypass the detection and negotiation phases; and proceed at
once with the fallback action specified in S36. Can be used to force MNP.

S82 - Break Handling Options

S82 is for compatibility purposes only, changing this register will not have any affect.

S86 - Call Failure Reason Code

When the modem issues a NO CARRIER result code, a value is written to this S-Register to help
determine the reason for the failed connection. S86 records the first event that contributes to a NO
CARRIER message. The cause codes are:

Register Value Meaning

S86 =0 Normal hangup, no error occurred.
S86 = 1 Sync loss in ISDN mode
S86 = 2 Compression parameter error
S86 = 3 Call Waiting caused disconnect.
S86 = 4 Physical carrier loss.
S86 = 5 No error correction at the other end.
S86 = 6 No response to feature negotiation.
S86 = 7 This modem is async only; the other modem is sync only.
S86 = 8 No framing technique in common.
S86 = 9 No protocol in common.
S86 =10 Bad response to feature negotiation.
S86 =11 No sync information from the remote modem.
S86 =12 Normal hangup initiated by the remote modem.
S86 =13 Retransmission limit reached.
S86 =14 Protocol violation occurred.
S86 =15 Lost DTR.
S86 =16 Received GSTN cleardown.
S86 =17 Inactivity timeout.
S86 =18 Speed not supported.
S86 =19 Long space disconnect.

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 S Registers

Register Value Meaning

S86 =20 Key abort disconnect.
S86 =21 Clears previous disconnect reason.
S86 =22 No connection established.
S86 =23 Disconnect after three retrains.
S86 =24 V44 expander error
S86 =25 Channel reset used to hangup
S86 =26 Remote request due to call waiting
S86 =27 MOH timed out
S86 =28 Host disconnected while on-hold
S86 =29 Host disconnected during FRR

Range
0-23

Default
21

S91 - PSTN Transmit Attenuation Level in Analog Modulations

Sets the transmit attenuation level from 0 to 20 dBm in analog modulations (e.g., V.34, V.32 bis, V.22
bis, and tone modes) resulting in a transmit level from 0 to -20 dBm.

Range:
0 to 20 (0 to -20 dBm transmit level)

Default
10 (-10 dBm transmit level)

S92 - Fax Transmit Attenuation Level

Sets the transmit attenuation level from 10 to 15 dBm for the fax mode, resulting in a transmit level
from -10 to -15 dBm.

Range
10 to 15 (-10 to -15 dBm transmit level)

Default
10 (-10 dBm transmit level)

S95 - Extended Result Codes

The bits in this register can be set to override some of the Wn command options. A bit set to a 1 in this
register will enable the corresponding result code regardless of the Wn setting. Also, refer to Table 1.

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Bit Meaning
0 CONNECT result code indicates DCE speed instead of DTE speed.
1 Append/ARQ to CONNECT XXXX result code in error-correction mode (XXXX = rate; see
Table 1).
2 Enable CARRIER XXXX result code (XXXX = rate; see Table 1.
3 Enable PROTOCOL XXXX result code (XXXX = protocol identifier; see Table 1).
4 Reserved
5 Enable COMPRESSION result code (XXXX = compression type; see Table 1).
6 Reserved
7 Reserved

Default
0

S200 – Disable K56Plus Protocol

Enables/disables K56Plus protocol.

Bit(s) Meaning Values

0-4 Reserved
5 Disable K56Plus 0: Enable K56Plus
1: Disable K56Plus (Default)
6-7 Reserved

Default
4

S202 - CSM Bit Mapped Control Register

Controls K56flex/V90 Tx level and automatic modem status response.

Bit Meaning Values

0 K56Plus Protocol 0: Follows the setting of ATNn. (Default)
1: Forces LAPM when a K56Plus call is established
1 Enable V.90 digital pad 0: Disables V.90 digital pad compensation.
compensation
1: Enables V.90 digital pad compensation (Default)
2 Display Tx and Rx HNDSHK
states
3 Reserved (used for Diable
Auto-Gain on client server)

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 S Registers

Bit Meaning Values

4 Automatic modem status response 0: No automatic modem status response (requires
&V2 command) (Default)
1: Automatic modem status response before every
connect message and after every disconnect
message
5 K56flex Tx level select 0: -12 dBm (Default)
1: -6 dBm
6 V90 Tx level select 0: -12 dBm (Default)
1: -6 dBm
7 Enable V.42 selective reject 0: Disables V.42 selective reject (Default)
1: Enables V.42 selective reject

Default
2

S210 – Symbol Rate Limit

Limits the symbol rate for V.34.

Bit(s) Meaning Values

0-2 Symbol rate limit 0: 2400 only
1: 2400 only
2: 2400, 2800
3: 2400, 2800, 3000
4: 2400, 2800. 3000. 3200
5: 2400, 2800, 3000, 3200, 3429 (Default)
3 Asymmetric/symmetric rate 0: V.34 asymmetric rates disabled
select
1: V.34 asymmetric rates enabled (Default)
4-7 Reserved

Default
13 (0Dh)

S220 – Duration of Answer Tone

Modifies the duration of the answer tone.
Command is in units of 450 ms.
• 1 unit lower decreases answer tone duration by 450 ms
• 1 unit higher increases answer tone duration by 450 ms

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 S Registers

For +MS=11, +MS=12, or +MS=56 (even if automoding to a lower modulation):

Register Value Meaning

S220 > 15 Increase by 450 ms multiples for each unit greater than 15
S220 = 15 default +1800 ms (6760 ms)
S220 = 13 default +1350 ms (5850 ms)
S220 = 12 default +450 ms (5400 ms)
S220 = 11 default (4950 ms)
S220 = 10 default - 450 ms (4500 ms)
S220 = 9 default - 900 ms (4050 ms)
S220 = 7 default - 1350 ms (3155 ms)
S220 = 5 default - 2250 ms (2250 ms)
S220 < 5 Decrease by 450 ms multiples for each unit less than 5

For +MS = anything other than 11, 12, or 56

Register Value Meaning

S220 > 15 Increase by 450 ms multiples for each unit greater than 15
S220 = 15 default+1800 ms (5395 ms)
S220 = 13 default+900 ms (4500 ms)
S220 = 12 default+450 ms (4050 ms)
S220 = 11 default (3600 ms)
S220 = 10 default-450 ms (3150 ms)
S220 = 9 default-900 ms (2700 ms)
S220 = 5 default-1350 ms (906 ms)
S220 < 5 Decrease by 450 ms multiples for each unit less than 5

Default
11

S221 – Duration of Billing Delay

Modifies the duration of the billing delay.

Range
0-255 in 10 ms increments

Default
50 (500 ms)

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S222 – General purpose register

Bit Meaning
0 Disable Lucent negotiation with V.8bis
1 &V3 – outputs Ja sequence.

Range
0-255.

Default value
0

S223 – V.90 PCM Transmit level adjustment

V.90 transmit level can be varied from 0dbm to –16dbm. The allowed value range is 0 to 31.
DCE will output an Error, if input decimal value is greater than 31. Bit 6 of S202 must be zero for S223
to have any effect. If bit 6 of S202 is one, the TX level is restricted to –6dbm only and S223 will not have
any effect on V.90 transmit level.
Formula to convert dBm to S223 value is “dBm = -(S223+1)/2”. For example –12dBm = -(23+1)/2. S223
=23 is the default value after power up.

Default
-12db

S224 – Digital detect timer

This register is used to autodetect the incoming call from ISDN V110/V120 (UI and Multiframe) or
analog modem.

Values
100ms per unit

Range
0-100

Default
0. The default mode disables ISDN autodetect mode.

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 FAX Class 2 Commands

FAX Class 2 Commands

This section describes the fax class 2 commands. These commands are summarized in Table 24.

Command Syntax and Guidelines

DTE Commands
The ISO 646 character set (CCITT T.50 International Alphabet 5, American Standard Code for
Information Interchange) is used for the issuance of commands and responses. Only the low-order 7 bits
of each character are used for commands or parameters; the high order bit is ignored. Upper case
characters are equivalent to lower case characters.
For Phase C data transmission or reception, all 8 bits are needed.

DTE Command Lines

A command line is a string of characters sent from a DTE to the modem (DCE) while the modem is in
a command state. A command line has a prefix, a body, and a terminator. Each command line (with the
exception of the A/ command) must begin with the character sequence AT and must be terminated by a
carriage return. Commands entered in upper case or lower case are accepted, but both the A and T must
be of the same case, i.e., "AT" = ASCII 065, 084 or “at” = ASCII 097, 116. The body is a string of
commands restricted to printable ASCII characters (032 - 126). Space characters (ASCII 032) and
control characters other than CR (ASCII 013) and BS (ASCII 010) in the command string are ignored.
The default terminator is the ASCII <CR> character. Characters that precede the AT prefix are ignored.
The command line interpretation begins upon receipt of the carriage return character.

Facsimile Command Syntax

After the "AT" or "at" prefix, facsimile commands use extended syntax. Each command is preceded by
the “+F” character and consists of single characters and a decimal parameter (if applicable) terminated
by the semicolon “:” character (ASCII 059) or by the <CR> that terminated the command line. A missing
decimal parameter is evaluated as 0.
For example, the command to instruct the modem to automatically answer a data or fax call and also
enable reception is:
AT+FAE=0; +FCR 1 <CR>

Basic data mode and fax service class mode select commands are:
AT+FCLASS=0 <CR>for Data Mode
AT+FCLASS=2 <CR>for Service Class 2 Fax

In Class 2, the DCE makes and terminates calls, manages the communication session and negotiates
(T.30 protocol) and transports the image date to DTE. The T.4 protocol management of image data, etc.,
is done by DTE.
The response to
AT+FCLASS= 0<CR>in Data Mode

or
AT+FCLASS=2<CR>in Service Class 2 Fax

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 FAX Class 2 Commands

is
OK

The service class may be set by the DTE from the choices available using the “+FCLASS=<VALUE>”
command.

Table 24 Fax Class 2 Commands

Command Function
Service Class ID
+FCLASS= Service Class
Class 2 Action Commands
D Originate a Call
A Answer a Call
+FDT Data Transmission
+FET=N Transmit Page Punctuation
+FDR Begin or Continue Phase C Receive
Data
+FK Session Termination
Class 2 DCE Responses
+FCON Facsimile Connection Response
+FDCS: Report Current Session
+FDIS: Report Remote Identification
+FCFR Indicate Confirmation to Receive
+FTSI: Report the Transmit Station ID
+FCSI: Report the Called Station ID
+FPTS: Page Transfer Status
+FET: Post Page Message Response
+FHNG Call Termination with Status
Class 2 Session Parameters
+FMFR? Identify Manufacturer
+FMDL? Identify Model
+FREV? Identify Revision
+FDCC= DCE Capabilities Parameters
+FDIS= Current Sessions Parameters
+FDCS= Current Session Results
+FLID= Local ID String
+FCR Capability to Receive
+FPTS= Page Transfer Status
+FCR= Capability to Receive
+FAE Adaptive Answer

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Table 24 Fax Class 2 Commands (continued)

Command Function
+FBUF? Buffer Size (Read Only)
+FPHCTO Phase C Time Out
+FAXERR Fax Error Value
+FBOR Phase C Data Bit Order

General Rules

• +Fnnn commands must be entered completely, otherwise an ERROR response is sent.

• All response messages are preceded and followed by <CR><LF>. Multiple response commands
(e.g., +FDIS: +FCSI: and +FDCS:) will, therefore, appear to a have a blank line between them.
• Fax Class 2 commands can be separated by the “:” character. The “;” character can be omitted if
desired. Note that non-data commands cannot be separated by the “;” which is allowed as a dial
modifier.
• All Class 2 commands are assumed to be the final command on a command line. Additional
characters will be ignored.
• An ERROR message will be generated if a Class 2 action command is received while in data modem
mode:
– A Class 2 action command is received while in data modem mode.
– A Class 2 read-only parameter is given the “=” form of a +F command (e.g., AT+FAXERR=5).
– A Class 2 action command is given the inappropriate “=” or “=?” form (e.g., AT+FDR=?).

Serial Port Speed and Flow Control

During fax mode, the DTE-DCE port speed is 19200 bps.
The DCE provides a speed buffer of 1024 bytes and provides the DC1/DC3 (XON/XOFF) or RTS/CTS
method of controlling the data into the buffer. This flow control is controlled by the &K3 or &K4
command.
This method of data flow control is available only for DTE to DCE direction of data. There is no
provision for data flow control from DCE to DTE.

Data Stream Termination

The DCE exchanges streams of data with the DTE while executing data transfer commands. These data
streams use the termination described in Section “AT Commands Description,” on page 11.
The ASCII <DLE> character (016) is used as a special character to shield special characters. The
<DLE><ETX> character pair (<106><003>) is used to mark the end of a stream. The following patterns
are used:

Pattern Meaning
any data...<DLE><ETX> End of stream

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 FAX Class 2 Commands

Pattern Meaning
any data...<DLE><DLE> Single <DLE> in data
any data...<DLE><any byte> Delete <DLE><any byte>

DTE to DCE Streams

The DCE filters the data stream from the DTE, and removes all character pairs beginning with <DLE>.
The DCE recognizes <DLE><ETX> as the stream terminator. The DCE recognizes <DLE><DLE> and
reinserts a single <DLE> in its place.
The DTE must filter stream data to the DCE, and insert extra <DLE> characters ahead of data.

DCE to DTE Streams

The DTE must filter the data stream from the DCE, and remove all character pairs beginning with
<DLE>. The DTE must recognize <DLE><ETX> as the stream terminator. The DTE must recognize
<DLE><DLE> and reinsert a single <DLE> in its place.
The DCE filters stream data to the DTE, and inserts extra <DLE> characters ahead of data.

Auto Answer
The DCE can answer as a data DCE or as a fax DCE. It can answer the call adaptively, in that it can
determine whether the call is 'data' or 'fax'. The +FAA parameter controls this feature. Fax adaptive
answer operates only when +FCLASS=0.

Parameter Value Meaning

AT+FAA=1 Auto answer as a facsimile or a data modem depending on the call

DCE Response Meaning

CONNECT XXXX DCE status response if data call
+FCON DCE status response if fax call

Identification of T.30 Options

Group 3 devices negotiate session subparameters in DIS, DCS, and DTC frames. These subparameters
are defined in Table 25.

Session Status Reporting

The DCE provides reports to the DTE on the status of a session. The DCE provides the following status
reports:
1. Connection and hang up status:
a. +FCON
b. +FHNG:<0-255>

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2. Requested DIS session parameters in +FDIS: <string> report remote facsimile capabilities.
Syntax: +FDIS: VR, BR, WD, LN, DF, EC, BF, ST
3. +FDCS: <string> reports the negotiated parameters
4. Phase C prompts:
a. XON
b. XOFF
c. DC2
5. Phase C base status reports, depending upon copy quality and related end-of-page status:
a. +FPTS: <1-5>

Procedure Interrupt Negotiation

CCITT allows a station to request a procedure interruption at the end of a page. This request is passed
between stations by the PIP, PIN, and PRI-Q messages.

Service Class 2 Identification and Selection Commands

Three commands (+FMFR?, +FMDL?, +FREV?) report identification and selection information. Each
of these three commands cause the DCE to send a message to the DTE. The messages are programmable
using ConfigurACE.

+FMFR?, Request Manufacturer Identification

The +FMFR? command causes the DCE to send a message identifying the DCE product manufacturer.
The default message is:
ROCKWELL
OK

+FMDL?, Identify Product Model

The +FMDL? command causes the DCE to send a message identifying the DCE product model. The
default message is similar to:
RC96XXXAC
OK

+FREV?, Identify Product Revision

The +FREV? command causes the DCE to send a message identifying the DCE product model revision
number. The message format is the same as the ATI3 message, e.g.:
VX.XXX-model number
OK

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Service Class 2 Action Commands

These commands transfer data, and punctuate sessions. They also release specific T.30 messages. All
action commands must be the last command on a command line as indicated by the terminating <CR>.
All action commands initiate processes. The modem will not accept other commands from the DTE until
the modem issues a final result code (e.g., OK, CONNECT). The modem will abort the process if it
receives any character before the final result code is issued.

ATD, Originate a Call

The DCE can support a DTE command to originate a call using the ATD command (see the “AT
Commands Description” section on page 11).

Syntax
ATD....<CR>
If this command is unsuccessful, the DCE reports an appropriate failure or error type result code such
as NO CARRIER, NO DIALTONE, or BUSY (see the “Error Detection and Data Compression
Commands” section on page 64).
If this call is successful, the typical DCE response is:
• ATDnn..nn (go off-hook, dial, get CED)
• +FCON (DCE detects flags)
• [+FCSI:<remote ID string>]
• +FDCS:<T.30 subparameter string>
• OK

The DCE dials, detects call progress, and generates the CNG tone. It then waits for a DIS frame. On
detection of the first Phase B preamble (V.21 ch. 2 modulated by 300 bps HDLC flags), it reports the
“+FCON” message to the DTE. The DCE then switches to 19200 bps.
The DCE generates a DCS frame based on the received DIS frame and on the previously set +FDIS
parameter. A +FDT command from the DTE releases the DCE to transmit that DCS frame.
The DCE reports the initial received T.30 negotiation messages, including the DIS frame and the
optional CSI ID string. The +FDIS: report is followed by the OK final result code.

ATA, Answer a Call

The DCE can support a DTE command to answer an incoming call using the ATA command (see the
“AT Commands Description” section on page 11).
The DTE may issue an Answer command in response to an incoming ring.
If the Answer command is unsuccessful, the DCE will report an appropriate failure or error type result
code, such as NO CARRIER (see the “Error Detection and Data Compression Commands” section on
page 64).

Manual Call Answer

If this call is successful, the typical DCE response (answer and receive) is:
• +FCON

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• [+FTSI:<remote ID string>]
• +FDCS:<T.30 subparameter string>
• OK (DTE should issue +FDR command here)
Upon receipt of an Answer command from the DTE, the DCE answers and generates the CED tone. The
DCE then generates a DIS frame (derived from the +FDIS parameter) and hunts for the first T.30
negotiation frames. Upon detection of the first Phase B preamble (V.21 ch 2 modulated by 300 bps
HDLC flags), it reports the “+FCON” message to the DTE.
The DTE should report the initial received T.30 negotiation messages, including the DCS frame. The
+FDCS: report will be followed by the OK final result code.

Automatic Answer

The modem provides for automatic answering of incoming calls. If configured for automatic answer, the
modem answers an incoming call in compliance with T.30, and reports the same messages as described
for manual answer.

Connection as a Data Modem

If configured to do so by the +FAA parameter, the DCE will adaptively answer as a facsimile DCE or as
a data DCE. If the DCE answers as a data DCE, it resets the +FCLASS parameter to 0 and issues the
appropriate final result code (e.g., CONNECT, or NO CARRIER) to the DTE.

+FDT, Data Transmission

The +FDT command prefixes Phase C data transmission. When the DCE is ready to accept Phase C data,
it issues the negotiation responses and the CONNECT result code to the DTE.

Syntax
+FDT <CR>
In Phase B, the +FDT command releases the DCE to proceed with negotiation, and releases the DCS
message to the remote station. In Phase C, the +FDT command resumes transmission after the end of a
prior transmit data stream.

Initiate Page Transmission

Phase B DCE polled response:

• [+FCSI:<remote ID string> (if new CSI received)
• [+FDIS:<subparameters from remote station>] (if new DIS received)
• +FDCS:<T.30 subparameter string>
• CONNECT
• <XON> (when ready for data)
After placing a call, or after finishing a document exchange, the DTE may command the DCE to re-enter
T.30 Phase B to attempt to negotiate a document transmission.

Continue a Page

The DTE may issue more than one +FDT command for a given page, so that different files may be
concatenated together. These files must have the same format.

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• CONNECT
• <XON>

Phase C Data Framing

Phase C data must be presented to the DCE in stream mode. The DCE expects Phase C data to follow
until it detects <DLE><ETX> termination characters. The DCE will filter the stream as described in the
“Serial Port Speed and Flow Control” section on page 98.
The DCE will acknowledge the end of the data by returning the OK result code to the DTE.
If there is data underrun before the next +FDT or +FET= command, the DCE will zero-fill the pad as per
T.4 until the Phase C timeout (+FPHCTO) is reached, or until more data is received. The DCE appends
an RTC pattern to the transmit data after an +FET= command is received from the DTE.

Phase C Data Format

The Phase C data will be of the format specified by the negotiated T.30 DCS frame. The +FDCS:<string>
response is defined in the “+FDCS:, Report Current Session Capabilities” section on page 110. The
subparameter values are described in Table 25.
The DCE will use the negotiated minimum Scan Time parameter from the DCS frame, and insert
sufficient fill bits to pad each line to the minimum scan time. This is reported in the +FDCS:ST
subparameter.
If the DCE finds more than one consecutive EOL in Phase C data (e.g., RTC), it will send only one EOL.
• Phase C data must conform to T.4 specifications.
• The DTE need not include a final RTC, since the DCE will append an RTC in response to an FET=
command.
• Some facsimile machines may treat two EOLs as an RTC.

Table 25 T.30 Session Subparameter Codes

Label Function Value Description

VR Vertical Resolution 0 Normal, 98 lpi
1 Fine, 196 lpi
1
BR Bit Rate +FDCS (originate) +FDIS (answer)
0 2400 bps/V.27 ter V.27 ter (2400 only)
1 4800 bps/V.27 ter V.27 ter
2 7200 bps/V.29 V.29, V.27 ter
3 9600 bps /V.29 or V.17 V.29, V.27 ter
4 12000 bps/V.33 or V.17 V.17, V.33, V.29, V.27 ter
5 14400 bps/V.33 or V.17 V.17, V.33, V.29, V.27 ter
WD Page Width 0 1728 pixels in 215 mm
1 2048 pixels in 255 mm
2 2432 pixels in 303 mm
32 1216 pixels in 151 mm
2
4 864 pixels in 107 mm

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Table 25 T.30 Session Subparameter Codes (continued)

Label Function Value Description

LN Page Length 0 A4, 297 mm
1 B4, 364 mm
2 unlimited length
DF Data Compression Format 0 1-D modified Huffman
2
1 2-D modified Read
2
2 2-D uncompressed
mode
32 2-D modified modified
Read
EC Error Correction 0 Disable ECM
2
(Annex A/T.30) 1 Enable ECM, 64
bytes/frame
22 Enable ECM, 256
bytes/frame
BF Binary File Transfer 0 Disable BFT
2
1 Enable BFT
ST Scan Time/Line VR = normal VR = fine
0 0 ms 0 ms
1 5 ms 5 ms
2 10 ms 5 ms
3 10 ms 10 ms
4 20 ms 10 ms
5 20 ms 20 ms
6 40 ms 20 ms
7 40 ms 40 ms
1. CCITT T.30 does not provide for the answering station to specify all speeds exactly using the DIS frame. Implementation of
some BR codes (e.g., code 2) by an answering DCE is manufacturer specific.
2. Not supported.

<CAN>, Escape from Transmission

The DCE may request the DTE to halt Phase C transmission, by sending a cancel <CAN> character (024)
to the DTE. In this case, the DTE should terminate Phase C transmission, issue <CAN>, and wait for the
OK response code from the DCE.

+FET, Transmit Page Punctuation

This command is used to punctuate page and document transmission after one or more +FDT commands.
This command generates T.30 Post Page Messages selected by the <ppm> code (Table 26).

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Syntax
+FET=<ppm>[,<pc>,<bc>,<fc>]

DCE response
+FPTS:<ppr>- when received from remote OK
The +FET=<ppm> command indicates that the current page is complete; no more data will be appended
to it. The value indicates whether there are any additional pages are to be sent and, if so, whether there
is a change in any of the document parameters.
The DTE can command the DCE to generate PRI-Q messages with the +FET=<ppm> command using
ppm codes 4-6 (Table 26).
This command must be sent within the time out specified by +FPHCTO after sending Phase C data, or
else the DCE will end the page and document transmission. If the Phase C timeout is reached, the DCE
sends an EOP post page message and terminates the session.
The remote facsimile station should respond to the post page message with a post page response. The
DCE will report this using the +FPTS:<ppr> response (Table 27).

Table 26 T.30 Post Page Message Codes

ppm Code Mnemonic Description

0 [PPS-]MPS Another page next, same document
1 [PPS-]EOM Another document next
2 [PPS-]EOP No more pages or documents
3 PPS-NULL Another partial page next
4 [PPS-]PRI-MPS Another page, procedure interrupt
5 [PPS-]PRI-EOM Another doc., procedure interrupt
6 [PPS-]PRI-EOP All done, procedure interrupt
=8+ppm Post Page Message (ppm code)

Table 27 T.30 Post Page Response Messages

ppr Code Mnemonic Description

1 MCF Page good
2 RTN Page bad; retrain requested
3 RTP Page good; retrain requested
4 PIN Page bad; interrupt requested
5 PIP Page good; interrupt requested

End a Page

The +FET= command causes the DCE to append an RTC (6 EOL) pattern as needed and enter Phase D
by sending the selected T.30 Post Page message.
The +FET=1 (EOM) command signals the remote station that the next document will have a new DCS
negotiated; this causes the session to re-enter Phase B.

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+FDR, Begin or Continue Phase C Receive Data

The +FDR command initiates transition to Phase C data reception. This can occur after answering,
dialing, a document is received, or a page is received.

Syntax
+FDR <CR>

Default value
3 seconds in some places
The DCE reports the negotiated T.30 parameters, with the remote ID information if available. When the
DCE is ready to commence data transfer, it issues a CONNECT response code. If the DCE cannot resume
data transfer because there is no more data, it responds OK. When the DTE is ready to accept data, it
issues an <DC2> character (018) to the DCE.
If the DTE issues an <XOFF> character to the DCE for flow control, the DCE signals the DTE when its
buffers are empty by sending a <DLE><DC2> (<016><018>) character pair.
When the DCE delivers the last byte of a page, the DCE reports the Page Transfer Status via the
+FPTS:<ppr> response (Table 27).
After a Page Transfer Status Report, the DCE reports the post page message from the remote facsimile
station with the +FET:<ppm> response (Table 26) which signals the intentions of the remote station.
The DCE holds the post page response message to the remote facsimile station (MCF, etc.), represented
in the +FPTS parameter until the next +FDR command. The DTE may modify the +FPTS parameter
before issuing the +FDR command which releases that message. The DTE must issue a +FDR command
to release Post Page Messages.

Initiate Document Reception

The +FDR command may be issued in Phase B after an answer command, or in Phase B after a previous
document.
The DCE response in stream mode is:
• +FCFR (when CFR sent)
• [+FTSI:<remote ID string>] (if new TSI received)
• [+FDCS:<T.30 subparameter string>] (if new DCS)
• CONNECT (<DC2> needed from DTE here)
• <Phase C data stream>
• <DLE><ETX>
• +FPTS:<ppr>, <lc> [,<blc>, <cblc>]
• +FET:<ppm>
• OK (DTE must issue +FDR command to release post page response)

Continue Document Reception

The DTE may issue a +FDR command in Phase D, which releases the post page message, and indicates
readiness to receive another page after receipt of a Multipage (+FET:0) or PPS-NULL (+FET:3)
message. The DCE response will be:
• CONNECT (<DC2> needed from DTE here)

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• <Phase C data stream)

• <DLE><ETX>
• +FPTS:<ppr>, <lc> [,<blc>, <cblc>]
• +FET:<ppm>
• OK (DTE must issue +FDR command to release post page response)
If done receiving:
• +FHNG: <hangup cause code>
• OK
Continue page reception

Phase C Data Framing

Phase C data may be presented to the DTE in stream mode. The DCE will transfer a stream of data to
the DTE, followed by the <DLE><ETX> stream termination characters. The DCE will filter the stream
as described in the “Serial Port Speed and Flow Control” section on page 98.

Phase C Data Format

The received data format is negotiated under T.30 reported by the +FDCS:VR,BR,WD,LN,DF,EC,BF,ST
response.
The DCE will delete the terminating RTC (6 EOLs) patterns.

<CAN>, Escape from Reception

From the +FDR command until the end of Phase D Date, the DCE is in a data transfer state, and will not
respond to DTE command characters. The DCE will respond to three ASCII control characters: <DC1>
(017) and <DC3> (019) flow control characters, and cancel <CAN> (024).
Upon receipt of the <CAN> character, the DCE will terminate the reporting of received data by sending
trailing <DLE><ETX> characters to the DTE, and will then execute an implied +FK command in order
to conduct an orderly disconnection.

+FK, Session Termination

The +FK command causes the DCE to terminate the session in an orderly manner. In particular, the DCE
will send a DCN message at the next opportunity and hang up. At the end of the termination process, the
DCE will report the +FHNG response with result code (Table 28).

Syntax
+FK
This operation can be invoked by using the cancel <CAN> character during Phase C data reception (see
prior section)
The DCE will wait until the current page completes, unless the reception is of unlimited length; in that
case, the DCE may halt reception and terminate the session at any time.

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Table 28 Hang Up Status Codes

Code Cause Description

0-9 Call Placement and Termination
0 Normal and proper end of connection
1 Ring Detected or Ringback Detected, but Fax HNDSHK never started (i.e., CED ANS
Tone, or HDLC Flags not detected)
2 Call aborted, from +FK or AN
3 No Loop Current
10-19 Transmit Phase A & Miscellaneous Errors
10 Unspecified Phase A error
11 CED ANS Tone, or HDLC Flags detected, but Fax HNDSHK not completed within
the T.30 T1 timeout period
20-39 Transmit Phase B Hangup Codes
20 Unspecified Transmit Phase B error
21 Remote cannot receive or send
22 COMREC error in transmit Phase B
23 COMREC invalid command received
24 RSPEC error
25 DCS sent three times without response
26 DIS/DTC received 3 times; DCS not recognized
27 Failure to train at 2400 bps or +FMINSP value
28 RSPREC invalid response received
40-49 Transmit Phase C Hangup Codes
40 Unspecified Transmit Phase C error
43 DTE to DCE data underflow
50-69 Transmit Phase D Hangup Codes
50 Unspecified Transmit Phase D error
51 RSPREC error
52 No response to MPS repeated 3 times
53 Invalid response to MPS
54 No response to EOP repeated 3 times
55 Invalid response to EOP
56 No response to EOM repeated 3 times
57 Invalid response to EOM
58 Unable to continue after PIN or PIP
70-89 Receive Phase B Hangup Codes
70 Unspecified Receive Phase B error
71 RSPREC error

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Table 28 Hang Up Status Codes

Code Cause Description

72 COMREC error
73 T.30 T2 timeout, expected page not received
74 T.30 T1 timeout after EOM received
90-99 Receive Phase C Hangup Codes
90 Unspecified Receive Phase C error
91 Missing EOL after 5 seconds
92 Unused code
93 DCE to DTE buffer overflow
94 Bad CRC or frame (ECM or BFT modes)
100-119 Receive Phase D Hangup Codes
100 Unspecified Receive Phase D errors
101 RSPREC invalid response received
102 COMREC invalid response received
103 Unable to continue after PIN or PIP
120-255 Reserved Codes
Note Some codes are not implemented.

+FCIG, Set Polling ID

This command allows setting the Local Polling ID string used in a CIG frame. The syntax of this
command is identical to +FLID.

Write syntax
+FCIG="<local ID string>"

Valid value
20-character ASCII string

Default value
Null string

+FLPL, Indicate a Document for Polling

This command allows setting up an answering modem to know that it has a document available for
polling. This allows a calling modem to receive this fax from the answerer.

Syntax
AT+FLPL=<value>

Valid Values
0: Document not available

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1: Document available

+FSPL, Enable Polling

This command allows setting up an originating modem to be able to request to receive a document from
a polled station.

Syntax
AT+FSPL=<value>

Valid Values
0: Request disallowed
1: Request allowed

Service Class 2 DCE Responses

The DCE sends information responses to the DTE as a facsimile session proceeds. They indicate the state
of the facsimile session and convey needed information. These messages are solicited messages
generated in execution of DTE action commands described in the “Service Class 2 Action Commands”
section on page 101.
The DCE precedes and follows the information responses with <CR><LF>.
The DCE provides the on-line status of several session parameters when they are available during T.30
handshaking. These include the remote ID string and the DIS/DCS parameters. These responses report
the T.30 session parameter frames. The subparameters are described in Table 25.

+FCON, Facsimile Connection Response

+FCON indicates connection with a fax machine. It is released by detection of HDLC flags in the first
received frame. +FCON is generated in response to an Originate or Answer command.

+FDCS:, Report Current Session Capabilities

+FDCS:<string> reports the negotiated parameters. Phase C data will be formatted as described by the
subparameters. This message may be generated in execution of +FDT or +FDR commands before the
CONNECT result code if new DCS frames are generated or received. (See Table 25)

Syntax
+FDCS:VR,BR,WD,LN,DF,EC,BF,ST

+FDIS:, Report Remote Station Capabilities

+FDIS:<string> reports remote facsimile station capabilities and intentions. The parameters are
provided in ASCII notation. (See Table 25)

Syntax
+FDIS:VR,BR,WD,LN,DF,EC,BF,ST
This message is generated in execution of Originate, Answer, +FDT, or +FDR commands.

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+FCFR, Indicate Confirmation to Receive

The DCE sends a +FCFR response to the DTE upon reception of an acceptable TCF training burst and
a valid DCS signal from the remote machine. This indicates that the DCE will receive Phase C data after
the remote station receives the local DCE's CFR message. The +FCFR message is generated in execution
of a +FDR command.

Syntax
+FCFR

+FTSI:, Report the Transmit Station ID

This response reports the received transmit station ID string, if any. This message is generated in
execution of Originate, Answer, +FDT, or +FDR commands.

Syntax
+FTSI: “<TSI ID string>” Transmit Station ID

+FCSI:, Report the Called Station ID

This response reports the received called station ID string, if any. This message is generated in execution
of Originate, Answer, +FDT, or +FDR commands.

Syntax
+FCSI: “<CSI ID string>” Called Station ID

+FPTS:, Receive Page Transfer Status

The +FPTS:<ppr> is generated by the DCE at the end of Phase C data reception in execution of a +FDR
command.

Syntax
+FPTS:<ppr>, <lc> [,<blc>, <cblc>]
The <ppr> is generated by the DCE; it depends on the DCE capabilities at T.4 error checking. See
Table 27 for <ppr> values.
The receiving DCE will count the lines. These values are:
• <lc> = line count
• <blc = bad line count
• <cblc> = <consecutive bad line count
A receiving DTE may inspect <ppr> and write a modified value into the +FPTS parameter. The DCE
will hold the corresponding Post Page Response message until released by a +FDR command from the
DTE.

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+FET:, Post Page Message Response

The +FET:<post page message> response is generated by a receiving DCE after the end of Phase C
reception on receipt of the post-page message from the transmitting station. The +FET:<ppm> response
is generated in execution of a +FDR command. The <ppm> codes respond to the T.30 post page
messages (Table 26).

Syntax
+FET:<ppm>

+FPTS:, Transmit Page Transfer Status

The +FPTS: response reports a <ppr> number representing the copy quality and related post-page
message responses received from the remote DCE. The valid <ppr> values are defined in Table 27.

Syntax
+FPTS:<ppr>
The +FPTS:<ppr> response is generated in execution of a +FET=<ppm> command.

+FHNG:, Call Termination with Status

+FHNG indicates that the call has been terminated. The hangup cause is reported and stored in the
+FAXERR parameter for later inspection. The <hangup status code> values are described in Table 28.

Syntax
+FHNG:<hangup status code>
+FHNG:<hsc> is a possible intermediate result code to any DTE action command described in the
“Service Class 2 Action Commands” section on page 101. It is always followed by the OK final result
code.
Upon termination of a call, the DCE determines the cause of termination and reports it as part of the
FHNG:<hsc> response. It also stores this <hsc> code in the +FAXERR parameter for later inspection.
The hangup values are organized according to the phases of the facsimile transaction as defined by T.30.
A COMREC error or RSPREC error indicates that one of two events occurred:
1. A DCN (disconnect) signal was received, or
2. An FCS error was detected and the incoming signal was still present after 3 seconds.
The table values are in decimal notation. Leading zero characters are optional.

+FCIG:, Report the Polled Station ID

This response reports the received transmit station ID string, if any. This message is generated in
execution of Originate, Answer, +FDT, or +FDR commands.

Syntax
+FCIG: “<ID string>” Polled Station ID

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+FDTC:, Report the Polled Station Capabilities

If the answerer has a document to poll, it would be communicated to the originator in bit 9 of the DIS
frame. The originating station may elect to transmit a fax, and later, send SIG and DTC frames to pick
up the polled document. The answering station would report the incoming DTC frame via the +FDTC:
response message after command mode is cancelled with the AT+FDR command.

Syntax
+FDTC: “<string>” Polled Station Capabilities

+FPOLL, Indicate Polling Request

This message is sent to the DTE if the received DIS message indicates that the remote station has a
document to poll (by bit 9 in the DIS) and polling has been enabled with the AT+FSPL command. The
DTE may then decide to receive rather than transmit.

Syntax
+FPOLL:

Service Class 2 Parameters

All Service Class 2 parameters can be read, written, and tested for range of legal values by the DCE. The
general syntax is described in the “Command Syntax and Guidelines” section on page 96.
Group 3 FAX devices negotiate session parameters in DIS, DCS, and DTC frames. The following
parameters are provided to condition the facsimile DCE for the capabilities it will offer and to report the
session settings negotiated.
The three primary T.30 session parameters are +FDCC, +FDIS and +FDCS. They are compound
parameters, using values listed in Table 25. Figure 1 illustrates their relationships.

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Figure 1 T.30 Session Parameter Relationships

+FDCC, DCE Capabilities Parameters

+FDCC allows the DTE to sense and constrain the capabilities of the facsimile DCE from the choices
defined in CCITT T.30 Table 2. When +FDCC is modified by the DTE, the DCE copies +FDCC into
+FDIS.

Write syntax
+FDCC=VR,BR,WD,LN,DF,ED,BF,ST

Valid values
See Table 25

Default values
0,3,0,2,0,0,0,0 (9600 bps fax models)
or
0,5,0,2,0,0,0,0 (14400 bps fax models)

+FDIS, Current Sessions Capabilities Parameters

The +FDIS parameter allows the DTE to sense and constrain the capabilities used for the current session.
The DCE uses +FDIS to generate DIS or DTC messages directly, and uses +FDIS and received DIS
messages to generate DCS messages.

Write syntax
+FDIS=VR,BR,WD,LN,DF,EC,BF,ST

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Valid values
See Table 25

Default values
0,3,0,2,0,0,0,0 (9600 bps fax models)
or
0,5,0,2,0,0,0,0 (14400 bps fax models)
The DCE initializes the +FDIS parameter from the +FDCC parameter on initialization, when +FDCC is
written, and at the end of a session.

+FDCS, Current Session Results Parameters

The +FDCS parameter is loaded with the negotiated T.30 parameters for the current session. A
transmitting DCE generates DCS; a receiving DCE gets DCS from the remote station. The DTE may
read this parameter.

Read Syntax
+FDCS?

DCE response
+FDCS=VR,BR,WD,LN,DF,EC,BF,ST
or
FDCS=

Valid values
See Table 25

Default values
0,0,0,0,0,0,0,0
The +FDCS parameter is initialized 0,0,0,0,0,0,0,0 upon initialization and at the beginning of a session.
If the DTE issues a +FDCS? command in the initial state, the DCE reports:
<CR><LF>0,0,0,0,0,0,0,0<CR><LF>

The contents of +FDCS are spontaneously reported during execution of +FDR or +FDT commands by
the +FDCS:VR,BR,WD,LN,BF,EC,BF,ST response using the same compound parameter format.
Several commands and responses reference T.30 session negotiated parameters. These are described by
a set of common subparameters. These subparameters are described in Table 25 with notes. Optional
parameter values are marked with footnote 2. Unspecified parameter values are reserved for future use.
The +FDCC, +FDIS, and +FDCS compound parameters use these session parameters (On writes,
unspecified subparameters are unchanged.)
The +FDIS:, +FDCS:, and +FDTC: session report responses use these subparameters.
For test response, ranges of values are reported for each subparameter enclosed in parentheses
characters. For example, a DCE response to +FDCC=? could report:
<CRLF> (0,1), (0-5), (0-3), (0-2), (0-2), (0-2), (0), (0-7) <CRLF> (14400 fax models)

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Example
+FDIS=0,5,0,2,0,0,0,1 =
• VR = 0 (98 dpi vertical resolution)
• BR = 5 (14400 bits)
• WD = 0 (1728 pixels)
• LN = 2 (unlimited length)
• DF = 0 (1-D modified Huffman coding)
• EC = 0 (no ECM)
• BF = 0 (no BFT)
• ST = 1 (5 ms scan time)

+FLID=, Local ID String

Write syntax
+FLID="<local ID string>"

Valid value
20-character ASCII string

Default value
Null string
If FLID is not a null string, it generates a TSI or CSI frame. CCITT Table 3/T.30 includes digits 0-9, “+”
and space.
If the DCE supports use of CCITT Table 3/T.30 only, the response to a +FLID=? command is “(20) (32,
43, 48-57).” If the DCE supports printable ASCII <, the response is: “(20) (32-127)<CRLF>.” The first
“(20)” represents string length, the second (character values) field reports supported string values.
• The string is saved in RAM.
• Non-numeric characters are not filtered out.
• The string is right justified.

+FCR, Capability to Receive

Write syntax
+FCR=<value>

Valid values
0 or 1

Default value
0
+FCR=0 indicates that the DCE will not receive message data. This can be used when the DTE has
insufficient storage. The DCE can send and can be polled for a file.
+FCR is sampled in CCITT T.30 Phase A and Phase D.

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+FPTS=, Page Transfer Status

The +FPTS parameter contains a value representing the post page response, including copy quality and
related end-of-page status. These values correspond to post page response messages defined in T.30. The
receiving DCE sets this parameter after it receives a page of Phase C data. The transmitting DCE sets
this parameter with the status reported by the receiving station. The DTE may inspect or modify this
parameter.

Write Syntax
+FPTS=<ppr>

Valid values
1, 2, 3, 4, 5

Default value
0
The set of <ppr> values is defined in CCITT Table 6-4. These values are also reported in the +FPTS
response to the +FDR command.

+FCQ, Copy Quality Checking

This parameter controls Copy Quality checking by a receiving facsimile DCE.

Write syntax
+FCQ=<value>

Valid values
0

Default value
0
The DCE returns +FCQ=0 which indicates the DCE does no quality checking. The DCE will generate
Copy Quality OK (MCF) responses to complete pages, and set +FPTS=1.

+FPHCTO, DTE Phase C Response Time-out

The +FPHCTO command determines how long the DCE will wait for a command after reaching the end
of data when transmitting in Phase C. When this time-out is reached, the DCE assumes there are no more
pages and no documents to send. It then sends the T.30 EOP response to the remote device.

Write syntax
+FPHCTO=<value>

Valid values
0 - 255, 100 millisecond units.

Default value
30

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+FAXERR, T.30 Session Error Report

This read-only parameter indicates the cause of the hangup. CCITT Table 6-5 shows the valid values for
this parameter as well as the meaning of the each value. +FAXERR is set by the DCE at the conclusion
of a fax session. The DCE resets +FAXERR to 0 at the beginning of Phase A off-hook time.

Read syntax
+FAXERR= <table value>, read only

Valid values
0 - 255, see CCITT Table 6-5 for meaning

+FBOR, Data Bit Order

This command controls Phase C data (T.4 encoded data) transferred during execution of +FDT or +FDR
commands.

Write syntax
+FBOR=<value>

Valid values
0, 1, 2, or 3

Default value
0
This parameter controls the mapping between PSTN facsimile data and the DTE-DCE link. There are
two choices:
• Direct: The first bit transferred to each byte on the DTE-DCE link is the first bit transferred on the
PSTN data carrier.
• Reversed: The last bit transferred of each byte on the DTE-DCE link is the first bit transferred on
the PSTN data carrier.
The following two codes are supported:
• +FBOR = 0 or 2 selects direct bit order for Phase C data.
• +FBOR = 1 or 3 selects reversed bit order for Phase C data.

Note This parameter does not affect the bit order of control characters generated by the DCE.

+FAA, Answer Parameter

+FAA=0 constrains the DCE to answer as set by +FCLASS.
+FAA=1 indicates that the DCE can answer and automatically determine whether to answer as a Class
2 facsimile DCE or as a data modem. If the DCE automatically switches, it modifies FCLASS
appropriately.

Write syntax
+FAA=<value>

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Valid values
0 or 1

Default value
0
Fax adaptive answer operates only when +FCLASS=0.
Class 2 adaptive answer is implemented as follows:
1. First, a data mode handshake is attempted. If the DCE has been configured for automode detection
(using the +MS command), the DCE may try several protocols before terminating attempts to make
a data mode connection. This can take as long as 6-8 seconds.
2. If the data mode connection attempt fails, a facsimile Class 2 connection is assumed. When a
connection is made as a result of the adaptive answer, the DCE issues the DATA or FAX result code
before the CONNECT or +FCON message to inform the DTE of the connection type. After making
a Class 2 connection, the DCE stays on-line.

+FBUF?, Buffer Size

The +FBUF parameter allows the DTE to determine the characteristics of the DCE's data buffer. Data
buffers are used for flow control. Use of the reported values allow the DTE to transfer data without
provoking XOFF.

Read syntax
+FBUF?

DCE response syntax

<bs>, <xoft>, <xont>, <bc>, where:
• <bs> = total buffer size
• <xoft> = XOFF threshold
• <xcont> = XON threshold
• <bc> = current buffer byte count

Example
+FBUF?
512, 506, 500, 0

Example Sessions
Table 29 and Table 30 show the typical commands and responses for sending and receiving two pages,
respectively.

Table 29 Send Two Pages, 1-D Data, No Errors

DTE Command DCE Response Local DTE Action Remote Station Action
AT+CLASS=2 OK Set Class 2 x
AT+FLID="<local ID>" OK Set local ID

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 FAX Class 2 Commands

Table 29 Send Two Pages, 1-D Data, No Errors (continued)

DTE Command DCE Response Local DTE Action Remote Station Action
AT<dial string> Off hook, dial Answer,
Send CNG Send [CED]
+FCON Detect flags V.21 flags
[+FCSI:"<csi>"] [Get CSI] [CSI]
+FDIS: <dis codes> Get DIS DIS
OK
AT+FDT [Send TSI] [Get TSI]
Send DCS Get DCS
+FDCS:<DCS codes> Send TCF Get TCF
CONNECT Get CFR Send CFR
<XON> Send carrier Receive carrier

<1st page data> Send page data Receive page data

<DLE><ETX> OK
AT+FET=0 Send RTC Get RTC
Get MPS Get MPS
+FPTS:1 Get MCF Send MCF
OK
AT+FDT CONNECT Send carrier Receive carrier
<XON>
<2nd page data> Send page data Receive page data
<DLE><ETX> OK
AT+FET=2 Send RTC Get RTC
Send EOP Get EOP
+FPTS:1 Get MCF Send MCF
+FHNG:0 Send DCN Get DCN
OK Hang up Hang up

Table 30 Receive Two Pages, 1-D Data, No Errors

DTE Command DCE Response Local DTE Action Remote Station Action
AT+FCR=1 OK Enable reception
AT+FLID="<local ID>" OK Set local ID
RING Detect ring Dials[, Send CNG]
ATA Off hook
Send CED Get CED
Send CSI Get CSI
Send DIS Get DIS
+FCON Detect flags Send V.21 flags
[+FTSI:"<tsi>"] [Get TSI] [Send TSI]
+FDCS:<dcs codes> Get DCS Send DCS
OK Begin TCF receive Start TCF

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 FAX Class 2 Commands

Table 30 Receive Two Pages, 1-D Data, No Errors (continued)

DTE Command DCE Response Local DTE Action Remote Station Action
AT+FDR Accept TCF Finish TCF
+FCFR Send CFR Get CFR
[+FDCS:"<dcs codes>]
CONNECT Get page carrier Send pager carrier
<DC2> Get page data Send page data
<page data stream>
<DLE><ETX> Detect RTC Send RTC
+FPTS:1, <lc> Drop carrier
+FET:0 Get MPS Send MPS
OK
AT+FDR Send MCF Get MCF
CONNECT Get page carrier Send page carrier
<DC2> Get page data Send page data
<page data stream>
<DLE><ETX> Detect RTC Send RTC
+FPTS:1, <lc> Drop carrier
+FET:2 Get EOP Send EOP
OK
AT+FDR Send MCF Get MCF
+FHNG:0 Get DCN Send DCN
OK

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