1xBTS is an experimental CDMA2000 1x base station and core-network stack implemented primarily in Rust. It includes BTS, BSC, MSC, HLR, SMSC, packet data, voice, SDR radio backends, and a web dashboard for development and operation.

This project is intended for research, interoperability testing, and lab use. Operate RF hardware only where you are authorized to transmit. You have been warned.

While CDMA2000 was a major technology in the US and some other places around the world, it was never as ubiquitious as other standards like GSM. Up until now there has never been a way to revive old CDMA2000 devices. I started this project to change that.

1xBTS is under active development. The current stack can run as a network-in-a-box process for local integration, or split BTS/BSC operation over the included Abis transport. Support varies by handset, radio backend, channel configuration, and service option.

Currently many things are working (SMS, Voice, Packet Data) and while they work there is still much work to be done for production hardening. It still is a lot of fun though.

The Rust workspace keeps first-party crates flat under crates/ and external integration wrappers under external/:

• crates/ - CDMA protocol, RAN, core-network, packet, voice, and tooling crates.
• external/ - SDR, SIP/native, and other outside-library wrapper crates.
• 1xbts-web - Next.js dashboard backed by the management gRPC APIs.
• proto - protobuf service definitions.

Full documentation lives at 1xbts.org/docs.

The stack implements the full 3GPP2 1x reference architecture, with each node running as its own process and communicating over standard reference points:

• BTS (cdma-bts) - air-interface PHY/MAC, SDR-driven radio.
• BSC (cdma-bsc) - radio resource management; speaks Abis to the BTS.
• MSC (cdma-msc) - circuit-switched core; speaks A1 to the BSC.
• HLR (cdma-hlr) - subscriber database (PostgreSQL-backed).
• SMSC (cdma-smsc) - short message service center.
• PCF (cdma-pcf) - packet control function; A8/A9 to BSC, A10/A11 to PDSN.
• PDSN (cdma-pdsn) - packet data serving node, FoU/TUN packet path.
• voice-gw (cdma-voice-gw) - SIP gateway for outbound voice calls (PSTN origination). See voice gateway setup for trunk + STUN configuration.
• NIB (cdma-nib) - network-in-a-box launcher that runs the full stack in one process.

At minimum:

• Rust toolchain with Cargo.
• PostgreSQL for HLR/SMSC state (docker compose up -d postgres starts a local 1xbts database on port 45432).
• protoc for protobuf code generation (Ubuntu/Debian: protobuf-compiler).
• pkg-config and a C compiler for native bindings.
• libclang for bindgen (Ubuntu/Debian: libclang-dev).

Optional radio and voice dependencies depend on enabled features and hardware: UHD/USRP, LimeSuite, SoapySDR, bladeRF, and Baresip libre/re.

Common packages (always required):

sudo apt-get install -y \
    build-essential pkg-config protobuf-compiler libssl-dev \
    libclang-dev libre-dev

Then add the packages for whichever SDR backend(s) you plan to enable:

bladeRF (--features bladerf-backend):

sudo apt-get install -y libbladerf-dev

UHD / USRP (--features uhd-backend):

sudo apt-get install -y libuhd-dev

LimeSDR (--features lime-backend):

sudo apt-get install -y liblimesuite-dev

• bladeRF Micro 2.0
• Ettus USRP B210 (UHD)
• LimeSDR Mini v2

Other SoapySDR-compatible devices may work but are not regularly exercised.

• Apple iPhone (CDMA)
• Motorola V60s
• Qualcomm QCP-860
• Nokia Lumia 735
• Samsung SCH-U340
• BlackBerry 8830

Clone, bring up the support services, and run the network-in-a-box:

git clone https://github.com/chrismoos/1xbts.git
cd 1xbts

# Linux:
sudo modprobe fou ipip   # load kernel modules required by fou-nat
docker compose up -d --build

# macOS (uses bridge networking + host.docker.internal):
docker compose -f docker-compose.yml -f docker-compose.macos.yml up -d --build

# postgres :45432 · dashboard :3000 · fou-nat :17012 · speed test :5656
cargo run --release -p cdma-nib --no-default-features --features bladerf-backend -- \
    --config-dir config \
    --radio-config config/radio_bladerf_micro2.json

Default service ports are listed in docs/PORTS.md. If port 3000 is already in use, set ONEXBTS_WEB_PORT, for example ONEXBTS_WEB_PORT=3001 docker compose up 1xbts-web. Use --build after pulling repo updates so Compose rebuilds images that copy local files, such as fou-nat and speedtest. The packet-data speed test is available on the host at http://localhost:5656 by default, and from mobile packet-data clients at http://speed/ or http://speed.local.1xbts.org/.

To customize a config without editing the checked-in defaults, drop a sibling <name>.local.json next to it (e.g. config/bts.local.json). The loader deep-merges the local file on top of the base before validation. *.local.json is gitignored. See the Configuration guide. Packet-data DNS advertised to mobiles is configured in config/pdsn.json under packet.primary_dns and packet.secondary_dns; the checked-in defaults point to the FOU gateway resolver so speed and speed.local.1xbts.org resolve locally.

Enable exactly one SDR backend at build time:

Run focused tests while developing:

cargo test -p cdma-bts
cargo test -p cdma-bsc

The dashboard ships in 1xbts-web (Next.js) and is started by docker compose up above. To run it directly:

cd 1xbts-web
npm install
npm run dev

• GitHub Discussions — github.com/chrismoos/1xbts/discussions for questions, ideas, and show-and-tell.
• GitHub Issues — github.com/chrismoos/1xbts/issues for bug reports and feature requests.
• IRC — #1xbts on Libera.Chat for live chat.

The main 1xBTS workspace is licensed under Apache-2.0. The SDR wrapper crates under external/ (bladerf, bladerf-sys, limesuite, limesuite-sys, uhd, uhd-sys) are dual-licensed MIT OR Apache-2.0; see the individual Cargo.toml files for package-level license metadata.

The optional native Baresip libre/re dependency used by the SIP voice gateway is provided by the system and is distributed upstream under BSD-3-Clause terms.