No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.

BSC Routing

DN99567018
Issue 3-0

GSM in Single RAN

Rel. 24R2-SR
Operating Documentation, Issue 01

© 2024 Nokia. Nokia Condential Information. Use subject to agreed restrictions on disclosure and use.
BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Nokia is committed to diversity and inclusion. We are continuously reviewing our customer
documentation and consulting with standards bodies to ensure that terminology is inclusive
and aligned with the industry. Our future customer documentation will be updated
accordingly.

This document includes Nokia proprietary and condential information, which may not be
distributed or disclosed to any third parties without the prior written consent of Nokia. This
document is intended for use by Nokia’s customers (“You”/”Your”) in connection with a
product purchased or licensed from any company within Nokia Group of Companies. Use this
document as agreed. You agree to notify Nokia of any errors you may nd in this document;
however, should you elect to use this document for any purpose(s) for which it is not
intended, You understand and warrant that any determinations You may make or actions
You may take will be based upon Your independent judgment and analysis of the content of
this document.

Nokia reserves the right to make changes to this document without notice. At all times, the
controlling version is the one available on Nokia’s site.

No part of this document may be modied.

NO WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
ANY WARRANTY OF AVAILABILITY, ACCURACY, RELIABILITY, TITLE, NON-INFRINGEMENT,
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, IS MADE IN RELATION TO THE
CONTENT OF THIS DOCUMENT. IN NO EVENT WILL NOKIA BE LIABLE FOR ANY DAMAGES,
INCLUDING BUT NOT LIMITED TO SPECIAL, DIRECT, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL OR ANY LOSSES, SUCH AS BUT NOT LIMITED TO LOSS OF PROFIT,
REVENUE, BUSINESS INTERRUPTION, BUSINESS OPPORTUNITY OR DATA THAT MAY ARISE
FROM THE USE OF THIS DOCUMENT OR THE INFORMATION IN IT, EVEN IN THE CASE OF
ERRORS IN OR OMISSIONS FROM THIS DOCUMENT OR ITS CONTENT.

Copyright and trademark: Nokia is a registered trademark of Nokia Corporation. Other

product names mentioned in this document may be trademarks of their respective owners.

© 2024 Nokia.

Important Notice on Product Safety

This product may present safety risks due to laser, electricity, heat, and other
sources of danger.

Only trained and qualied personnel may install, operate, maintain or otherwise
handle this product and only after having carefully read the safety information
applicable to this product.

The safety information is provided in the Safety Information section in the “Legal,
Safety and Environmental Information” part of this document or documentation
set.

2 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Nokia is continually striving to reduce the adverse environmental effects of its products and
services. We would like to encourage you to join us in working towards a cleaner and safer
environment. Please recycle product packaging and follow the recommendations for power
use and proper disposal of our products.

Should you have any questions regarding our Environmental Policy or the environmental
services we offer, please contact us at Nokia for any additional information.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 3

Use subject to agreed restrictions on disclosure and use.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
No further reproduction or networking is permitted. Distributed by Nokia.

Issue 3-0

Use subject to agreed restrictions on disclosure and use.

© 2024 Nokia. Nokia Confidential Information
BSC Routing

4
BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table of Contents

Summary of changes .................................................................................................................... 9

1 Routing in BSC ............................................................................................................................ 12

1.1 BSC Routing overview .................................................................................................... 13

2 Working states of circuits ......................................................................................................... 14

3 Allowed working state changes for trunk circuits ................................................................. 16

4 System states of working circuits ........................................................................................... 27

5 Circuit hunting ............................................................................................................................ 31

6 Dual seizure prevention method ............................................................................................. 33

7 Semipermanent connections ................................................................................................... 35

8 Displaying circuit groups or trunk circuits by state .............................................................. 36

9 Creating TDM circuit groups ..................................................................................................... 37

10 Adding circuits to circuit groups ........................................................................................... 40

10.1 Steps ............................................................................................................................... 40

11 Adding circuits to CCS circuit groups using free CIC allocation ....................................... 42
11.1 Steps ............................................................................................................................... 43

12 Creating routes ........................................................................................................................ 44

12.1 Steps ............................................................................................................................... 45

13 Adding circuit groups in a route ............................................................................................ 46

13.1 Steps ............................................................................................................................... 46

14 Changing the working state of a circuit ............................................................................... 48

14.1 Steps ............................................................................................................................... 48

15 Changing the working state of a circuit group .................................................................... 49

15.1 Steps ............................................................................................................................... 49

16 Changing the working state of a route ................................................................................ 50

16.1 Steps ............................................................................................................................... 50

17 Selecting the hunting method ............................................................................................... 51

17.1 Steps ............................................................................................................................... 51

18 Creating semipermanent connections ................................................................................. 52

18.1 Steps ............................................................................................................................... 53

19 Deleting circuits from circuit groups .................................................................................... 54

19.1 Steps ............................................................................................................................... 54

20 Deleting circuit groups ............................................................................................................ 55

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 5

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
20.1 Steps ............................................................................................................................... 56

21 Deleting routes or circuit groups from routes ................................................................... 57

21.1 Steps ............................................................................................................................... 58

22 Routing does not work as expected ..................................................................................... 59

22.1 Steps ............................................................................................................................... 59

23 Problems with circuits ............................................................................................................. 60

23.1 Steps ............................................................................................................................... 60

6 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
List of Figures
Figure 1 BSC routing hierarchy ................................................................................................ 12
Figure 2 Circuit group and circuit hunting ............................................................................. 31

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 7

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
List of Tables
Table 1 Routing capacity figures ............................................................................................. 13
Table 2 Circuit states ................................................................................................................. 14
Table 3 Additional states of circuits ........................................................................................ 14
Table 4 Reservation states of circuits .................................................................................... 15
Table 5 The working state changes of bidirectional circuit with MML commands .......... 16
Table 6 The working state changes of bidirectional circuit with MML commands when the
illegal state is BL ............................................................................................................ 17
Table 7 The working state changes of bidirectional circuit with MML commands when the
illegal state is SE ............................................................................................................. 18
Table 8 The working state changes of bidirectional circuit with MML commands when the
illegal state is TE ............................................................................................................. 19
Table 9 The working state changes of bidirectional circuit with MML commands when the
illegal states are BL and SE ........................................................................................... 19
Table 10 The working state changes of bidirectional circuit with MML commands when the
illegal states are BL and TE .......................................................................................... 20
Table 11 The working state changes of bidirectional circuit with MML commands when the
illegal states are SE and TE ........................................................................................... 21
Table 12 The working state changes of bidirectional circuit with MML commands when the
illegal states are BL+SE+TE .......................................................................................... 21
Table 13 The working state changes of an incoming circuit with MML commands ......... 22
Table 14 The working state changes of an incoming circuit with MML commands when the
illegal state is BL or BL + SE ......................................................................................... 22
Table 15 The working state changes of an incoming circuit with MML commands when the
illegal state is SE ............................................................................................................. 23
Table 16 The working state changes of an incoming circuit with MML commands when the
illegal state is TE or SE + TE ......................................................................................... 23
Table 17 The working state changes of an incoming circuit with MML commands when the
illegal state is BL + TE or BL + SE + TE ........................................................................ 24
Table 18 The working state changes of an ougoing circuit with MML commands .......... 24
Table 19 The working state changes of an ougoing circuit with MML commands when the
illegal states are BL or SE or BL + SE .......................................................................... 25
Table 20 The working state changes of an ougoing circuit with MML commands when the
illegal states are TE or its different combinations ................................................... 25
Table 21 System states of external circuit ............................................................................ 27
Table 22 Conditions of external circuit .................................................................................. 28
Table 23 System states of internal circuit ............................................................................. 28
Table 24 Condition of internal circuit ..................................................................................... 28
Table 25 Explanation of system state bits ............................................................................. 29
Table 26 Names of semipermanent circuit groups .............................................................. 52

8 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Summary of changes

Changes between document issues are cumulative. Therefore, the latest document issue contains
all changes made to previous issues.

Changes made between issues 3–0 and 2–2

Changed the structure of the document. The chapters were broken into smaller pieces with one
subject matter in one chapter.

Section Deleting subdestination was removed because subdestinations are not used in BSC.

Circuit hunting
Corrected the purpose of hunting to be to find a free circuit in the route, not destination.
Removed the first step about selecting the route using digit analysis and subdestination, because
they are not used in BSC. Updated the figure Circuit group and circuit hunting: the maximum
number of circuit groups has increased from 2048 to 4096.

Creating TDM circuit groups

Changed the name of the chapter from Creating external circuit groups. Added the missing
parameter list.

Adding circuits to circuit groups

Added steps 1, 2 and 4 into the procedure. Updated the example from a rarer occurrence to a
more common one.

Adding circuits to CCS circuit groups using free CIC allocation

New chapter.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 9

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Creating routes
In further information, deleted the sentence about taking the external route into use by creating a
digit analysis for it, because digit analysis in not used in BSC. In the example, deleted the step
about changing the state of the route into WO-EX because the state change is now automatic.

Adding circuit groups in a route

Added steps 1 and 2 into the procedure.

Selecting the hunting method

Added 'or reverse method 1 (METHOD=0)' to the sentence about specifying the hunting method
with the method parameter. Deleted the examples Defining hunting method 1, Defining hunting
method 2 and Define fixed sequential hunting, since bidirectional circuit groups are not used in
BSC.

Deleting circuits from circuit groups

Removed the note about not being able to delete all the circuits in a circuit group because it is no
longer valid. Added step 1 to the procedure.

Deleting circuit groups

Added step 1 to the procedure.

Deleting routes or circuit groups from routes

In the first paragraph, removed the sentence about deleting digit analysis, because digit analysis is
not used in BSC.

Routing does not work as expected

Deleted the first step (Check the route data), because digit analysis is not used in BSC. Added the
commands CEL and CRN to the step Check the working state of the circuits and circuit groups.

10 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Problems with circuits
Added a note about using the CEC command.

Changes made between issues 2–1 and 2–0

Corrected link names.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 11

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
1. Routing in BSC

The primary purpose of routing is to locate free circuits in the switching network in order to direct
calls to the desired number or destination. The routing functions of the exchange are used to:

examine where the call is going

find the best route to the desired location

In BSC, routing is used to create circuits, circuit groups and routes between BSC and MSC.

A diagram of BSC routing hierarchy is shown below:

Figure 1: BSC routing hierarchy

1. Outgoing route is an external route that is used to direct the call to another exchange. The
route contains the outgoing circuit groups and the signalling data.
2. Circuit group contains the circuits (timeslots) that are connected to another exchange and
through which calls are transferred to another exchange.
3. Hunting group is a subset of circuits in a hunted circuit group.
4. Circuit connects BSC and MSC.

Routing capacity of the DX 200 system

The capacity of the DX 200 system is partly fixed, partly determined by the SW build. The
following table gives the maximum capacity:

12 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 1: Routing capacity figures

Component Capacity Determined by

circuit groups 2 048 SW build

routes 4 096 SW build

circuit groups per route 8 fixed

circuits per circuit group 4 096 fixed

special routes about 65 000 SW build

1.1 BSC Routing overview

BSC routing descriptions and referential material BSC routing instructions

Routing in BSC Integrate

Working states of circuits Displaying circuit groups or trunk circuits by
Allowed working state changes for trunk circuits state
System states of working circuits Creating TDM circuit groups
Circuit hunting Adding circuits to circuit groups
Dual seizure prevention method Adding circuits to CCS circuit groups using
Semipermanent connections free CIC allocation
Creating routes
Adding circuit groups in a route
Optimise and Expand
Changing the working state of a circuit
Changing the working state of a circuit group
Changing the working state of a route
Selecting the hunting method
Creating semipermanent connections
Deleting circuits from circuit groups
Deleting circuit groups
Deleting routes or circuit groups from routes
Trouble Management
Routing does not work as expected
Problems with circuits

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 13

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
2. Working states of circuits

The following states are possible for circuits:

Table 2: Circuit states

Output State Meaning

WO working Circuit can transmit traffic normally

BA barred The circuit cannot transmit outgoing traffic

BL blocked The circuit cannot transmit incoming traffic

SE separated Neither incoming nor outgoing calls can be transmitted

(state of bidirectional circuit)

NU not used Transmission of calls has been disabled in one or both

directions

TE testing The circuits are used for making test calls

Circuits can also have the following additional states:

Table 3: Additional states of circuits

Output State Meaning

US user User has defined the state for the circuit

SY system State of the circuit has been given by the system

RS restart Circuit is restarting

EX executing Circuit is in use

LC local Circuit has been brought to WO-state in the own exchange,

but the connected exchange has not yet done so (for CCS
connections)

RC received Circuit has been set to BA-state by the connected exchange

at the other end (for CCS connections)

Possible fault conditions are indicated with the value FA or FAULTY.

14 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Circuit reservation states are indicated by:

Table 4: Reservation states of circuits

Output State Meaning

ID idle The circuit is idle

BU busy The circuit is busy

The state of the circuits of all but semipermanent circuit groups becomes automatically NU-US
when they are connected to a circuit group. This working state has to be changed into WO-EX
before the circuits can transmit traffic.

The way the state of the circuits is changed to transmit calls depends on the type of circuit group:

Circuits of a bidirectional circuit group: change the circuits in NU-US state first into SE, then
into WO.
Circuits of an outgoing circuit group: change the circuits in NU-US state first into BA, then into
WO.
Circuits of an incoming circuit group: change the circuits in NU-US state first into BL, then into
WO.

The circuits of semipermanent circuit groups are automatically set to WO-EX. For more
information, see Changing the working state of a circuit.

For more information, see Displaying circuit groups or trunk circuits by state and Deleting circuit
groups.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 15

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
3. Allowed working state changes for trunk circuits

The working state changes that the user is allowed to make to trunk circuits are presented in the
following tables according to the direction and the illegal state/states of trunk circuits:

Table 5: The working state changes of bidirectional circuit with MML commands

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 0 1 0

WO Working 0 -- 1 1 1 1

BL Blocked 0 1 -- 1 1 1

BA Barred 0 1 1 -- 1 1

SE Separated 1 1 1 1 -- 1

TE Test state 0 X X X X --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

16 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 6: The working state changes of bidirectional circuit with MML commands when the illegal
state is BL

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 0 1 0

WO Working 0 -- 0 1 1 1

BA Barred 0 1 0 -- 1 1

SE Separated 1 1 0 1 -- 1

TE Test state 0 X 0 X X --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 17

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 7: The working state changes of bidirectional circuit with MML commands when the illegal
state is SE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 1 0 0

WO Working 0 -- 1 1 0 1

BL Blocked 0 1 -- 1 0 1

BA Barred 1 1 1 -- 0 1

TE Test state 0 X X X 0 --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

18 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 8: The working state changes of bidirectional circuit with MML commands when the illegal
state is TE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 0 1 0

WO Working 0 -- 1 1 1 0

BL Blocked 0 1 -- 1 1 0

BA Barred 0 1 1 -- 1 0

SE Separated 1 1 1 1 -- 0

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 9: The working state changes of bidirectional circuit with MML commands when the illegal
states are BL and SE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 1 0 0

WO Working 0 -- 0 1 0 1

BA Barred 1 1 0 -- 0 1

TE Test state 0 X 0 X 0 --

1 change allowed

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 19

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
0 change not allowed

X change allowed if the preceding state was the same

Table 10: The working state changes of bidirectional circuit with MML commands when the illegal
states are BL and TE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 0 1 0

WO Working 0 -- 0 1 1 0

BA Barred 0 1 0 -- 1 0

SE Separated 1 1 0 1 -- 0

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

20 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 11: The working state changes of bidirectional circuit with MML commands when the illegal
states are SE and TE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 1 0 0

WO Working 0 -- 1 1 0 0

BL Blocked 0 1 -- 1 0 0

BA Barred 1 1 1 -- 0 0

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 12: The working state changes of bidirectional circuit with MML commands when the illegal
states are BL+SE+TE

State before the State after the change

change

NU WO BL BA SE TE

NU Not in use -- 0 0 1 0 0

WO Working 0 -- 0 1 0 0

BA Barred 1 1 0 -- 0 0

1 change allowed

0 change not allowed

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 21

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
X change allowed if the preceding state was the same

Table 13: The working state changes of an incoming circuit with MML commands

State before the change State after the change

NU WO BL TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 1

BL Blocked 1 1 -- 1

TE Test state 0 X X --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 14: The working state changes of an incoming circuit with MML commands when the illegal
state is BL or BL + SE

State before the change State after the change

NU WO BL TE

NU Not in use -- 1 0 0

WO Working 1 -- 0 1

TE Test state 0 X 0 --

1 change allowed

0 change not allowed

22 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
X change allowed if the preceding state was the same

Table 15: The working state changes of an incoming circuit with MML commands when the illegal
state is SE

State before the change State after the change

NU WO BL TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 1

BL Blocked 1 1 -- 1

TE Test state 0 X X --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 16: The working state changes of an incoming circuit with MML commands when the illegal
state is TE or SE + TE

State before the change State after the change

NU WO BL TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 0

BL Blocked 1 1 -- 0

1 change allowed

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 23

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
0 change not allowed

X change allowed if the preceding state was the same

Table 17: The working state changes of an incoming circuit with MML commands when the illegal
state is BL + TE or BL + SE + TE

State before the change State after the change

NU WO BL TE

NU Not in use -- 1 0 0

WO Working 1 -- 0 0

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 18: The working state changes of an ougoing circuit with MML commands

State before the change State after the change

NU WO BA TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 1

BA Barred 1 1 -- 1

TE Test state 0 X X --

1 change allowed

0 change not allowed

24 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
X change allowed if the preceding state was the same

Table 19: The working state changes of an ougoing circuit with MML commands when the illegal
states are BL or SE or BL + SE

State before the change State after the change

NU WO BA TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 1

BA Barred 1 1 -- 1

TE Test state 0 X X --

1 change allowed

0 change not allowed

X change allowed if the preceding state was the same

Table 20: The working state changes of an ougoing circuit with MML commands when the illegal
states are TE or its different combinations

State before the change State after the change

NU WO BA TE

NU Not in use -- 0 1 0

WO Working 0 -- 1 0

BA Barred 1 1 -- 0

1 change allowed

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 25

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
0 change not allowed

X change allowed if the preceding state was the same

For instructions, see Displaying circuit groups or trunk circuits by state and Changing the working
state of a circuit.

26 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
4. System states of working circuits

System states of external and internal circuits are set according to the arrays below.

In the following table, state (ST) describes the main state and substate of circuit. The state
depends on system bits, the direction of circuit (DIR), omitted state (OS), and priority (PRI). State
analysis is started from array top to bottom. State is possible when at least one system bit
matches both the direction and the omitted state. If there are several possible states, the current
state is selected according to priority. The selected state is the state whose priority is nearest to
the WO-EX state priority.

The condition of the circuit is FAULTY if any of the faulty bits has been set on. The same kind of
priority order is used in the condition field as in the STATE field.

Table 21: System states of external circuit

ST 31 . . . BITS . . . 0 DIR OS PRI

WO-EX 00000000 00000000 00000000 00000000 1

SE-SY 00000000 00000000 00000000 00111111 BI 2

BA-SY 00000000 00000000 00000000 00111111 BI SE 2

BA-SY 00000000 00000000 00000000 00111111 OUT 2

BL-SY 00000000 00000000 00000000 00111111 IN 2

SE-SY 00000000 00000000 10000100 10000000 3 (*)

BA-SY 00000000 00001101 00001011 00000000 4

BA-RC 00000000 00000000 01110000 00000000 5

BL-SY 00000000 00000010 10000000 01000000 6

BL-LC 00000000 00000000 00000100 00000000 7

(*) If fba_ccr system bit is not on, there must be one of next bits on:

00000000 00001101 01111011 00000000

Otherwise the state is not possible.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 27

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 22: Conditions of external circuit

ST 31 . . . BITS . . . 0 PRI

FAULTY 00000000 00000001 00101010 11101001 1

SIG-RS 00000000 00000000 00000001 00000000 2 (*)

(*) Condition SIG-RS is possible only when the state of circuit is BA-SY.

Table 23: System states of internal circuit

ST 31 . . . BITS . . . 0 PRI

WO-EX 00000000 00000000 00000000 00000000 1

BA-SY 00000000 00000000 01000000 00011111 2

Table 24: Condition of internal circuit

FAULTY 00000000 00000000 00000000 00010000

28 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Table 25: Explanation of system state bits

Bit Name Explanation of system state bits

0 se_iru IRUTIN has blocked and barred circuit while loop test
execution

1 se_et RCXPRO has blocked and barred circuit result from user
actions

2 se_ecu IWMANA has blocked and barred circuit result from user
actions

3 se_tc Circuit has been blocked and barred result from

TransCoder state changes

4 fse_pse PSEMAN has blocked and barred circuit result from PCM
failure

5 se_sta Statistical programs have separated circuit or unclassified

separating

6 fbl_tc TFHPRB has blocked circuit result from TC-failure

7 fba_ccr Circuit is barred due to continuity check failing

8 ba_rs Circuit is barred during the signalling start. The bit is set
also when circuit's direction is incoming.

9 fba_sig Circuit is barred due to a breaking of the signalling

10 lc_info The remote exchange does not yet acknowledge sent

messages

11 rba_sw Circuit is barred on the basis of received signalling

indicating a software blocking

12 rba_ub Circuit is barred on the basis of received signalling

indicating a user blocking

13 rba_f Circuit is barred on the basis of the received signalling

indicating a blocking caused by a hardware failure

14 rba_z Unclassified barring on the basis of the received signalling

15 bl_ss Circuit is blocked due to remote end barring

16 fba_dcme Circuit has barred by DCME equipment

17 bl_qua Quasi associated circuit has been blocked by EI1PRB

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 29

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Bit Name Explanation of system state bits

18 ba_dsp Circuit is barred due to a signal processing faulty or

overload

19 ba_asdis Circuit is barred due to a disconnect resource from AS. Bits

20 to 31 are not in use.

See Displaying circuit groups and trunk circuits by state, Working states of circuits and Allowed
working state changes for trunk circuits for more information.

30 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
5. Circuit hunting

The main purpose of hunting is to find a free circuit in the route.

Hunting goes through the following phases:

1. A free circuit group is selected from among the ones connected to the route, according to one
of the following methods:
a. The first circuit group is selected; either the circuit group that has been connected to the
route first, or defined as the first one (using the ORD parameter), when adding circuit
groups into the route.
b. The circuit group is selected according to sequential hunting; the search begins from the
circuit group following the one previously used, and the search continues in a fixed order.
2. The search for a free outgoing circuit is begun within a hunting group; all free circuits in the
circuit group form a chain, and a suitable one is selected according to one of the hunting
principles available in the DX 200 system.

Figure 2: Circuit group and circuit hunting

Defining the hunting method

The hunting method defines which circuit in the chain of circuits is hunted. This depends on when
the circuit was last released.

The following hunting methods are available in the DX 200 system:

Longest time free

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 31

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
The circuit that has been free for the longest time in the hunting group is selected.
Shortest time free
The circuit that has been free for the shortest time in the hunting group is selected.
Circular hunting (default)
Circular or cyclic hunting is a method which hunts the circuits consecutively, that is, the search
begins from the circuit following the one previously used, and the search continues in a fixed
order.
Fixed sequential hunting
A method of hunting where the selection of a free circuit always begins from the same circuit
and then moves to the next available circuit and so on, in a fixed order.

For instructions, see Creating routes.

For more information, see Dual seizure prevention method and Selecting the hunting method.

32 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
6. Dual seizure prevention method

Dual seizure is a situation where two network elements using the same circuits on a bidirectional
circuit group attempt to reserve the same circuit (timeslot) at the same time.

A dual seizure is detected by an exchange if it receives an initial address message for a circuit, for
which it has also sent an initial address message, before receiving a valid backwards message.

When a dual seizure is detected, the call being processed by the controlling exchange for that
circuit will be completed and the initial address message received from the other exchange will be
disregarded. The call being processed by the controlling exchange is allowed to mature. The call
being processed at the other end, however, will be terminated and the path is released. No
release message is sent. This exchange will automatically make a repeat attempt on the same or
an alternative route.

You can prevent dual seizure by defining the parameter METHOD, when creating a bidirectional
CCS circuit group.

The methods used are described below:

Method 1
Instead of two hunting groups, the exchanges form one hunting group out of the circuits in the
bidirectional circuit group. For these circuits, the two exchanges use an opposite order of
selection, that is, one begins the hunting from the first circuit in the circuit group, the other from
the last, as agreed.

Method 2
The circuits are divided into two hunting groups. Both exchanges get control (priority access) for
the circuits in one of these hunting groups. Both exchanges get priority access to that group of
circuits in the bidirectional circuit group which it is controlling. For these circuits, the hunting
method longest time free (first in - first out) is used. For the other half of the circuits, which are
controlled by another exchange, the hunting method shortest time free (last in - first out) is used.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 33

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Other methods
We recommend that you use either one of the methods described above. Other methods for
circuit selection may also be used, provided that they give the same degree of protection against
dual seizure, even when the partner exchange uses one of the methods specified by ITU-T.

For more information, see Circuit hunting.

34 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
7. Semipermanent connections

Semipermanent connections are external 64 kbit/s-connections in the exchange that subscribers

can use for, for example, data transfer. It is possible to build:

a semipermanent point-to-multipoint broadband connection between external PCM circuits

from an undirectional circuit to more than one outgoing circuit
a semipermanent broadband connection between two external PCM circuits

These connections are managed with the commands of the command group RB.

A semipermanent connection is always created for a specific circuit group. These circuit groups
are handled with the commands of the command group RC.

For instructions, see Creating semipermanent connections.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 35

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
8. Displaying circuit groups or trunk circuits by state

Use the command CEL to display the data on circuit groups or trunk circuits based on their state.
For instance, you can display all active (working) circuits on one or several circuit groups. Or, you
can display all circuits which are not in active state (WO).

For instructions, see Creating routes.

For more information, see Working states of circuits.

36 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
9. Creating TDM circuit groups

Purpose
External circuit groups are created to connect circuits between two exchanges. The circuits are
used for carrying speech or data between the network elements. The circuit group identifies the
direction and register signalling. The direction determines the kind of traffic that can go through
the circuits (outgoing, incoming, or bidirectional).Register signalling refers to the signalling type
that is used between the exchanges.

The parameters of the command RCC determine the basic data for the circuit group. Circuits are
added with the RCA command. Further features are added with the RCM or RCN commands.

Before you start

You should check the following before you create the circuit group:

Check the units and network connections:

Make sure that the cartridges, functional units (the PCM interface) and plug-in units (PIUs) have
been installed and tested in the exchange so that internal circuit groups, routes and PCM
circuit connections are operational.
Check that the signalling network and the signalling points between the exchanges have been
defined so that the network element is incorporated into the existing network. For instructions
on how these links are configured, see Common Channel Signalling (MTP, SCCP and TC).
Find out the signalling point code of the partner exchange.

Check the values needed for the following parameters:

Name of circuit group (NCGR): Check if there are specific conventions to use for
naming the circuit groups (NCGR) in the exchange.
Number of circuit group (CGR): Check if there are specific conventions to use for
numbering the circuit groups in the exchange. The parameter is not obligatory, and if you do
not give a number, the system selects a free number outside the range of 128 to 255). Do not
use numbers 128–255: they are reserved for special purposes and should therefore not be
used for external connections.
Direction: must be the same for all circuit groups connected to the same route. The circuit
group is bidirectional if it is used for both incoming and outgoing traffic, or it can be defined
for only incoming (for example from PBX or MSC to BSC) or outgoing (for example from the

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 37

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
BSC to MSC or PBX) connections.
Signalling point code (SPC): Find out the signalling point code of the partner
exchange. You can display the codes using the command NET.
Line signalling (LSI): This is a parameter required for control actions on circuit. Find out
the type of line signalling to be used for the circuit group. The available signalling types can be
seen in the CNTROL file, where each name is associated with a set of parameters. The
parameter is given simply as the 5 last characters of a record in the CNTROL file.
Method: This parameter is obligatory for bidirectional CCS circuit groups. It determines the
hunting order and hunting method for the circuits on circuit group, according to Signalling
System No. 7 Req. Q.724 and Q.764 (ITU-T Blue Book). The hunting method is used to
prevent dual seizure.

▪ Create an external circuit group

Some or all of the above mentioned parameters must be given, depending on the type of
the circuit group. The guidance shows only those parameters that are obligatory or freely
selectable for each circuit group type, once you have selected the type and other parameters
in the first parameter block.

ZRCC:TYPE=<cgr type>,NCGR=<circuit group name>,CGR=<circuit

group number>:DIR=<direction>,NET=<network
indicator>,SPC=<signalling point code>,LSI=<line
signalling>:METHOD=<dual seizure preventing method>;

Postrequisites

Note:
The state of the circuit group becomes barred (BA-US) when it is created. The state must
be changed into WO-EX before it can be used. For instructions, see Changing the working
state of a circuit group.

Example:Creating an incoming circuit group

To create an incoming circuit group called MARKFR whose number is 1, give the command below.
Create the circuit group in a network whose identifier is NA0.

ZRCC:TYPE=CCS,NCGR=MARKFR,CGR=1:DIR=IN,NET=NA0,SPC=H'391,LSI=AINA0;

For more information about routing, see Routing in BSC. For more information about circuit
groups, see Adding circuits to circuit groups and Deleting circuits from circuit groups. If you have

38 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
any problems, see Routing does not work as expected or Problems with circuits.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 39

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
10. Adding circuits to circuit groups

Purpose
The state of the circuits must be changed to WO-EX before they can be used. For instructions,
see Changing the working state of a circuit.

Further information

Example:Add circuits to circuit group

Add circuits to CCS circuit group named BERLIN. The number of the PCM system is 10. Physical
trunk circuit number is 15. The circuits in the circuit group are in hunting order 19-5, 19-6, 19-7,
19-8, and 19-9.

ZRCA:NCGR=BERLIN:ETPCM=15,CRCT=19-5&&-9:CCSPCM=10;

The execution printout is as follows:

CIRCUITS ADDED TO CIRCUIT GROUP

NCGR : BERLIN

FORMAT : ETPCM-PCM-TSL

: 15–19-5

: 15–19-6

: 15–19-7

: 15–19-8

: 15–19-9

TOTAL NUMBER OF CIRCUITS = 5

For more information about routing, see Routing in BSC and Creating routes. If you have any
problems, see Routing does not work as expected or Problems with circuits.

For more on this, see Circuit hunting.

10.1 Steps

1 Find free circuits

40 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
2 Interrogate the data on the connection

Use the RCI command.

3 Add circuits to circuit group

ZRCA:NCGR=<circuit group name>,CGR=<circuit group

number>:ETPCM=<etpcm>,CRCT=<circuit(s)>,BCRCT=<bit based
circuit>:CCSPCM=<number of PCM system>;

4 Change the state of the circuits

Use the CEC command.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 41

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
11. Adding circuits to CCS circuit groups using free CIC
allocation

Purpose

Note:
Free CIC allocation is used in ANSI environment.

Circuit Identification Code (CIC) is the exact number code for each circuit (timeslot) between two
exchanges. CIC is used by SS7 User Parts to point out the circuit to which the signalling message
in question is related to. Free CIC allocation makes the numbering of CIC totally independent from
PCM timeslot numbering.

The operators using the interconnection have to agree on the identical CIC numbering for the
circuits/timeslots between the two exchanges.

You can add up to 255 circuits at the same time for a CCS circuit group using free CIC. More
circuits can be added by repeating the command.

Note:
One timeslot in at least on one PCM connected to the same adjacent exchange must be
reserved for signalling purposes and should therefore not be connected as a speech
channel. The number of the channel varies from country to country.

Further information

Example:Adding circuits to CCS circuit group using free CIC allocation

1. Find free (unequipped) circuits that can be connected to the circuit group. If no free
(unequipped) circuits are available, create more with the WUC command.
2. Add circuits to CCS circuit group named BERLIN. The number of the physical trunk circuit is 15.
The circuits are 19-5, 19-7, 19-9, 19-11, and 19-13. Add CICs in an ascending order, starting from
the CIC 12345.
ZRCA:NCGR=BERLIN:ETPCM=15,CRCT=19-5&&-13,CRCTSTEP=1:
CIC=12345,CICDIR=0;

42 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
The execution printout is as follows:

CIRCUITS ADDED TO CIRCUIT GROUP

NCGR : BERLIN

FORMAT : ETPCM-PCM-TSL

: 15–19-5

: 15–19-7

: 15–19-9

: 15–19-11

: 15–19–13

TOTAL NUMBER OF CIRCUITS = 5

3. Change the state of the circuits.

ZCEC:ETPCM=15,CRCT=19-5&-7&-9&–11&–13:BL;
ZCEC:ETPCM=15,CRCT=19-5&-7&-9&–11&–13:WO;

11.1 Steps

1 Find free circuits

2 Add circuits to CCS circuit group using free CIC allocation

ZRCA:NCGR=<circuit group
name>:ETPCM=<etpcm>,CRCT=<circuit(s)>,CRCTSTEP=<step of
circuits>:CIC=<circuit identification code>,CICDIR=<direction of
CIC;

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 43

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
12. Creating routes

Purpose
The route is a collection of hunted circuit groups which have the same direction and which use the
same register signalling. The route establishes a path for outgoing calls.

The route determines the signalling method to be used for the connection. The route also
specifies the transmission medium type to be used.

Before you start

Check if there is an existing numbering plan which defines the range of routes (route numbers)
to be used for the type of connection you are creating.
Check that the circuit groups to be connected are available. They must be external and
bidirectional or outgoing. When connecting bidirectional circuit groups, check that the incoming
register signalling of the circuit group matches with the intended outgoing register signalling of
the route. The RCI command lists all circuit groups of the exchange.
Find a free route number. The RRI command lists numbers that are already in use.

Note:
Route numbers 128–255 are internal routes reserved for special purposes. Do not use
them for outgoing connections.

Find out the type of register signalling to be used for the route. The register signalling must be
one that has been defined in the exchange and it has to match the signalling type used in the
destination exchange. This can be found for example in the Signalling Descriptionsin the
Release Binder.

Further information

Example:Creating an outgoing route

1. Create an external route to which you connect two bidirectional circuit groups: HELSCCS1 and
HELSCCS2. Use a free route number (here 5). The outgoing register signalling must match the
equivalent incoming register signalling used.
ZRRC:EXT:ROU=5,OUTR=OFCH0,STP=2,NCGR=HELSCCS1&HELSCCS2;

44 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
For more information about routing, see Routing in BSC, Adding circuit groups in a route,
Changing the working state of a route and Deleting routes or circuit groups from routes. If you
have any problems, see Routing does not work as expected or Problems with circuits.

12.1 Steps

▪ Create the route (RRC).

ZRRC:EXT:ROU=<external route number>,OUTR=<outgoing register

signalling>, STP=<starting point for outgoing
dialling>,NCGR=<circuit group name>,TON=<type of number>;

Postrequisites
The working state of the route becomes automatically WO-EX when it is created.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 45

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
13. Adding circuit groups in a route

Purpose
The circuit groups to be added must already exist and they must be of the same type (outgoing
or bidirectional and using the same signalling) as the circuit groups that are already connected to
the route.

When you are connecting a bidirectional circuit group to the route, make sure that the incoming
register signalling matches the intended outgoing register signalling.

Further information

Example:Adding a circuit group into a route, to be used as first in hunting order

1. Interrogate the characteristics of the route (here 194) to check in which point in the hunting
order you want to add the circuit group.
ZRRI:GSW:ROU=194;
2. Check existing circuit groups. The type of the circuit group must match with the circuit group(s)
already connected to the route.
a. Interrogate which circuit groups have the same direction as the circuit groups already
connected to the route (here bidirectional).
ZRCI:SEA=2:DIR=BI;
3. Add circuit group BSSU2 to the route 194 of the GSW to be used as the first circuit group in
the hunting order.
ZRRA:GSW:ROU=194,NCGR=BSSU2,ORD=1;

For more information about routing, see Routing in BSC and Deleting circuit groups. If you have
any problems, see Routing does not work as expected or Problems with circuits.

13.1 Steps

1 Interrogate the characteristics of the route.

Use the RRI command.

2 Check existing circuit groups.

46 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Use the RCI command.

3 Add circuit groups in route.

ZRRA:GSW:ROU=<route number>,NCGR=<circuit group

name>,ORD=<ordinal number>:;

Postrequisites
The circuit groups can be added to a desired point in the hunting order by giving the ordinal
number of the first circuit group to be added. If no ordinal number is given, the circuit groups are
added at the end.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 47

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
14. Changing the working state of a circuit

14.1 Steps

▪ Change the working state of a circuit.

ZCEC:CRCT=<circuit>:<state>;

Postrequisites
Example:Changing the working state of circuits in an incoming circuit group

Bring circuits (5–2 to 5–15) in incoming circuit group from NU into WO (working state).

1. ZCEC:CRCT=5-2&&-15:BL;
2. ZCEC:CRCT=5-2&&-15:WO;

For more on working states of circuits, see Working states of circuits and Allowed working state
changes for trunk circuits. If you have any problems, see Routing does not work as expected or
Problems with circuits.

48 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
15. Changing the working state of a circuit group

Further information

See Allowed working state changes for trunk circuits, Adding circuits to circuit groups, Changing
the working state of a circuit and Changing the working state of a route for more information. If
you have any problems, see Routing does not work as expected or Problems with circuits.

15.1 Steps

1 Change the working state of circuit groups by using their number.

Bring circuit groups 3 and 5 to working state (WO).

1. Interrogate the state of circuit groups 3 and 5.

ZCRI:CGR=3&5;
2. If the state is BA, change it into WO.
ZCRM:CGR=3&5:WO;

2 Changing the working state of a circuit group by using its name.

Bring circuit group HELS2BI into working state (WO).

1. Interrogate the state of circuit group HELS2BI.

ZCRI:NCGR=HELS2BI;
2. If the state is BA, change it into WO.
ZCRM:NCGR=HEL2:WO;

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 49

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
16. Changing the working state of a route

Purpose
The working state of the route automatically becomes WO-EX when it is created. The other
possible state is BA (barred by the user).

If the working state needs to be changed, use the CRC command and specify the number of the
route to be changed (parameter ROU). The CRL command displays the states of the routes.

Further information

Example:Changing the working state of a route

Bar routes 25 and 32.

1. Interrogate the state of the routes.

ZCRL:ROU=25&32;
2. Change the state into BA.
ZCRC:ROU=25&32:BA;
The old and new state are displayed in the command printout.
3. To enable traffic on the route, bring it back to state WO.
ZCRC:ROU=25&32:WO;
The old and new state are displayed in the command printout.

See Routing in BSC and Allowed working state changes for trunk circuits for more information. If
you have any problems, see Routing does not work as expected or Problems with circuits.

16.1 Steps

▪ Change the working state of a route.

ZCRC:ROU=<route number>:<state>;

50 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
17. Selecting the hunting method

Purpose
You should define the hunting method according to one of the dual seizure prevention methods
described in the ITU-T Blue Book Q.764. For more information, see Dual seizure prevention
method.

In the DX 200 exchange, it is easiest to follow these recommendations by giving the method
parameter in the RCC command. This parameter specifies the hunting method according to the
ITU-T method 1 (METHOD=1) or reverse method 1 (METHOD=0) or method 2 (METHOD=2).

You can define another type of method by giving the METHOD=3 value in the RCC command. In
that case, you have to define hunting in more detail when adding circuits to the circuit group by
using the RCA command.

If you have given the METHOD=3 value in the RCC command, give the desired hunting method
using the RCN command.

Further information

Example:Define different hunting methods for two hunting groups

For hunting group 1 on circuit group TRECCS1, the hunting of the released circuits begins from the
last position, that is, the circuit which has been free for the longest time. For hunting group 2, the
hunting of the released circuits begins from the first position, that is, the circuit which has been
free for the shortest time.

ZRCN:NCGR=TRECCS1:HM1=LF,HM2=SF;

See Circuit hunting for more information. If you have any problems, see Routing does not work as
expected or Problems with circuits.

17.1 Steps

▪ Select the hunting method.

RCN:NCGR=<circuit group name>:HM1=<hunting method in first

hgr>,HM2=<hunting method in second hgr>;

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 51

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
18. Creating semipermanent connections

Purpose
To have a semipermanent connection, you must first create a special circuit group which is used
for semipermanent traffic. There can be two semipermanent circuit groups in the exchange.

The names of the semipermanent circuit groups are fixed, depending on the type of connection
for which they are used:

Table 26: Names of semipermanent circuit groups

Name Purpose

TSEM0 circuit group for trunk circuits

TSEM1 circuit group for trunk circuits

Before you start

1. Check that there is a circuit group which can be used for the semipermanent connection or
create one according to instructions.
2. Check that the circuits that you intend to use for the semipermanent connection are not
connected to any other circuit group. If they are connected to another circuit group, delete
them first from that circuit group (see examples below).

Further information

Example:Creating a semipermanent bidirectional connection

Create a semipermanent, bidirectional broadband connection between two external PCM circuits
with a bandwidth of 30 timeslots:

ZRBA:CRCT=12-1:CRCT=17-1:BW=30:BI;

Example:Creating a point-to-multipoint broadband connection

Create a semipermanent point-to-multipoint connection with a bandwidth of 31 timeslots from an

incoming PCM circuit to three outgoing PCM circuits:

ZRBB:CRCT=12-1:CRCT=17-1&18–1&22–1:BW=31;

52 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
Semipermanent broadband connections can be deleted with commands RBP and RBR. The same
parameters are given as when creating each of these connection types.

The semipermanent broadband connections of the exchange can be interrogated with the
command RBI.

For more information, see Semipermanent connections. If you have any problems, see Routing
does not work as expected or Problems with circuits.

18.1 Steps

▪ Create a semipermanent broadband connection.

See the specific examples below.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 53

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
19. Deleting circuits from circuit groups

Purpose
The circuits to be deleted must be in state NU-US before they can be deleted. The subscriber
counters must be turned off. For more information, see Changing the working state of a circuit.

Further information

Example:Removing circuits from circuit group

Removal procedure

1. Check the state of the circuits.

ZRCI:SEA=4:CRCT=21-1;
2. If the state is other than NU, change the working state of the circuits to be removed into state
NU. HEL1L is an incoming circuit group, so its working state must first be changed to BA, then
NU.
ZCEC:CRCT=21-1:BA:;
ZCEC:CRCT=21-1:NU:;
3. Delete the circuit 21-1 from circuit group HEL1L in group switch.
ZRCR:NCGR=HEL1L:CRCT=21-1;

If you have any problems, see Routing does not work as expected or Problems with circuits.

For further information, see Routing in BSC and Adding circuits to circuit groups.

19.1 Steps

1 Check the state of the circuits (RCI).

Use the RCI command.

2 Delete circuits from circuit group (RCR).

ZRCR:NCGR=<circuit group name>:CRCT=<circuits>;

54 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
20. Deleting circuit groups

Before you start

When deleting a circuit group, the state of the circuits belonging to the circuit group must be NU-
US, and the state of the circuit group must be BA-US. (State of semipermanent circuit groups
cannot be changed.)

The circuit group cannot be connected to any route. If the circuit group that you are deleting is
the last circuit group in the route, you must first delete the route with the RRD command, and
then the circuit group.

You can also delete semipermanent circuit groups that you have created.

Further information

Example:Removing a circuit group

1. Check that the circuit group to be deleted (HEL1L) is not connected to any route.
ZRRI:GSW:NCGR=HEL1L;
2. If it is connected to a route, remove it from the route or delete the whole route, using the RRD
command.
3. Change the working state of the circuits to be removed into state NU. HEL1L is an incoming
circuit group, so its working state must first be changed to BA, then NU. For more, see
Changing the working state of a circuit.
ZCEC:CRCT=21-1:BA:;
ZCEC:CRCT=21-1:NU:;
4. Delete circuit group HEL1L.
ZRCD:NCGR=HEL1L;

If you have any problems, see Routing does not work as expected or Problems with circuits.

For more information, see Creating TDM circuit groups.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 55

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
20.1 Steps

1 Check the state of the circuit group (RRI).

Check that the circuit group is not connected to a route with the RRI command.

2 Delete a circuit group (RCD).

ZRCD:NCGR=<circuit group name>;

56 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
21. Deleting routes or circuit groups from routes

Purpose
The whole route is deleted by giving the route number. You can also delete one or several circuit
groups from the route by giving the names of the circuit groups. However, at least one circuit
group must always remain in the route.

If an alternative route is deleted completely, it must not be connected to a routing sequence. If an

external route is deleted, it must not belong to any subdestination.

Note:
The command cannot be used if this is the last circuit group of the route. If you want to
delete even the last circuit group, that is, the whole route, give only the route number.

Further information

Example:Removing a circuit group from a route

Delete circuit group HEL1L from the external route number 14.

ZRRD:GSW:ROU=14,NCGR=HEL1L;

Example:Removing a route

Delete external route number 14.

ZRRD:GSW:ROU=14;

Note:
This command also removes the circuit group belonging to that route.

If you have any problems, see Routing does not work as expected or Problems with circuits.

For more information, see Adding circuit groups in a route.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 57

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
21.1 Steps

▪ Delete routes or circuit groups from routes (RRD).

ZRRD:GSW:ROU=<route number>,NCGR=<circuit group name>;

58 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
22. Routing does not work as expected

Purpose
If routing does not seem to work according to your plan, or you have a low call success ratio, you
can check the routing configuration.

22.1 Steps

1 Check the outgoing routes.

1. Check that the route is in correct working state

Use the CRL command.
Change the state into WO-EX, if necessary with the CRC command.
For more on the working states of circuits, see Working states of circuits.
2. Make the necessary modifications if you find faults in the route configuration
Use the RRM command.

2 Check the circuit group(s).

1. Check the working state of the circuits and the circuit group
You can check the state of the circuits with the CEL command. Change the state into WO-
EX, if necessary, with the command CEC.
You can check the state of the circuit groups with the command CRI and change their
state, if necessary, with the command CRM.
For more on working states of circuits, see Working states of circuits. For more on physical
problems with circuits, see Problems with circuits.
2. Check the direction of the circuit group
All circuit groups connected to the same route must have the same direction.
See Routing in BSC for more information. For instructions, see Creating TDM circuit
groups.

3 Make sure that the partner exchange also checks its configuration and makes the necessary
modifications.

Issue 3-0. © 2024 Nokia. Nokia Confidential Information 59

Use subject to agreed restrictions on disclosure and use.

BSC Routing

No further reproduction or networking is permitted. Distributed by Nokia.

Copyrighted material licensed to lcbantar@teco.com.ar on 30-05-2025.
23. Problems with circuits

Purpose
A faulty timeslot may be a physical problem in the circuit (problems with ET).

Further information

To avoid the complete failure of a circuit group, it is useful to connect circuits from more than one
ET to the circuit group.

If you have other routing related problems, see Routing does not work as expected.

Note:
With the CEC command you can check what causes the faulty state of the circuit.

23.1 Steps

1 Check the other timeslots on the same PCM.

2 Check the timeslots of other PCMs connected to the same circuit group.

3 Check the circuits of other circuit groups connected to the same route.

60 © 2024 Nokia. Nokia Confidential Information Issue 3-0

Use subject to agreed restrictions on disclosure and use.