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fixeria, 01/25/2024 11:32 PM
CSD (Circuit Switched Data)¶
- Table of contents
- CSD (Circuit Switched Data)
This page documents Circuit Switched Data support in the mobile application (see #4396).
L1 PHY support¶
At the time of writing this wiki page, CSD support is implemented for the following L1 PHYs:
- Layer1bin firmware for Calypso based phones
- SDR PHY (osmo-trx-ms) + trxcon application
- SDR PHY (grgsm_trx) + trxcon application
- FakeTRX (virtual Um) + trxcon application
L23 support state¶
- async (soft-UART) transparent V.110 calls
- [not tested] sync transparent V.110 calls
- [not tested] including fax calls
- TCH/F9.4, TCH/F4.8, TCH/F2.4 (only @ 2400 bps)
- [not tested] TCH/H4.8, TCH/H2.4 (only @ 2400 bps)
TODO/limitations¶
- non-transparent calls (V.110 RLP, V.120)
- TCH/F14.4 (see also #6167)
- TCH/F2.4 and TCH/H2.4 @ 300 bps, 1200/75 bps
- ECSD (multi-TCH support)
- CUSE
VTY configuration¶
Below is an example configuration snippet (only relevant params):
ms 1 support no full-data-14400 full-data-9600 full-data-4800 half-data-4800 full-data-2400 half-data-2400 tch-data io-handler unix-sock ! 'ti' is valid for Calypso PHY, change to 'osmo' for trxcon io-tch-format ti unix-socket /tmp/ms_data call-params type-rate 71 call-params ce transparent call-params async call-params async nr-stop-bits 1 call-params async nr-data-bits 8 call-params async parity none
(you can use osmo-config-merge
from libosmocore to merge this snippet into your mobile.cfg)
Call parameters¶
You can configure data call parameters either using call MS_NAME params
command:
OsmocomBB(mobile)> enable OsmocomBB(mobile)# call 1 params ? data Parameters for data calls OsmocomBB(mobile)# call 1 params data ? type-rate Type and rate (values like in AT+CBST; see 3GPP TS 27.007, section 6.7) ce Connection element (does not apply to FAX calls) sync Synchronous connection (always used for FAX calls) async Asynchronous connection (does not apply to FAX calls)
... or by entering the configuration node:
OsmocomBB(mobile)> enable OsmocomBB(mobile)# configure terminal OsmocomBB(mobile)(config)# ms 1 OsmocomBB(mobile)(ms)# tch-data OsmocomBB(mobile)(tch-data)# list ... io-handler (none|unix-sock|loopback) no io-handler io-tch-format (osmo|ti) unix-socket PATH call-params type-rate (4|5|6|7|68|70|71) call-params ce (transparent|non-transparent) [prefer] call-params (sync|async) call-params async nr-stop-bits <1-2> call-params async nr-data-bits <7-8> call-params async parity (none|even|odd|mark|space)
Below is the list of supported bearer type/rate combinations:
OsmocomBB(mobile)# call 1 params data type-rate? type-rate Type and rate (values like in AT+CBST; see 3GPP TS 27.007, section 6.7) OsmocomBB(mobile)# call 1 params data type-rate ? 4 2400 bps (V.22bis) 5 2400 bps (V.26ter) 6 4800 bps (V.32) 7 9600 bps (V.32) 68 2400 bps (V.110 or X.31 flag stuffing) 70 4800 bps (V.110 or X.31 flag stuffing) 71 9600 bps (V.110 or X.31 flag stuffing)
This list may be extended in the future, e.g. after adding support for TCH/[FH]2.4 @ 300 bps, 1200/75 bps.
Making calls¶
Making a data call is as easy as making a regular voice call:
OsmocomBB(mobile)# call 1 MSISDN ? [voice] Initiate a regular voice call (default) [data] Initiate a data call (UDI or 3.1 kHz audio) [fax] Initiate a data call (Facsimile group 3)
An incoming data call is answered just like a voice call:
OsmocomBB(mobile)# call 1 answer
After the call is connected (i.e. answered either locally or remotely), you can connect to the UNIX socket.
An ongoing call can be terminated just like a regular voice call:
OsmocomBB(mobile)# call 1 hangup
An incoming call can also be rejected using this command.
Example: sending text using socat
¶
socat UNIX-CONNECT:/tmp/ms_data STDIO,echo=0,icanon=0
Example: sending files using socat
and [xyz]modem
¶
On the receiving side:
socat UNIX-CONNECT:/tmp/ms_data EXEC:"lrzsz-rz -v"
On the sending side:
socat UNIX-CONNECT:/tmp/ms_data EXEC:"lrzsz-sz -v /usr/share/licenses/spdx/GPL-2.0-or-later.txt"
Updated by fixeria 6 months ago · 7 revisions