Osmocom Mobile Switching Centre
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Vadim Yanitskiy 1fc33f95d9 libmsc: reset the LU delay timer (X36) on MO/MT SMS
We don't want to delay the BSSAP/RANAP connection release any longer
than it takes to submit or deliver an SMS.  Thus, whenever a new SMS
transaction is being allocated, drop the LU token.

Change-Id: Iad4ace6038be4b6037e341e7d9d187bef2917d80
Related: osmo-ttcn3-hacks.git I74fa174ea649adb2112c8e471c0e339a2197a08d
Related: SYS#6913
2024-05-28 15:00:14 +07:00
.github Add funding link to github mirror 2024-03-23 12:36:00 +01:00
contrib contrib: remove rpm spec file 2024-05-08 14:41:07 +02:00
debian debian/postinst: add checks, be verbose 2024-05-14 15:21:05 +02:00
doc tweak example osmo-msc.cfg: 001 01 2024-02-08 23:42:17 +01:00
include libmsc: add timer X36 for delaying LU connections 2024-05-28 14:59:49 +07:00
m4 Drop unneeded ax_check_compile_flag.m4 2022-01-11 18:11:41 +01:00
src libmsc: reset the LU delay timer (X36) on MO/MT SMS 2024-05-28 15:00:14 +07:00
tests never page for TMSI with 'no assign-tmsi' 2024-03-28 04:06:58 +01:00
.gitignore Ignore .deb build byproducts 2022-08-01 13:53:37 +00:00
.gitreview update .gitreview to new repo url 2017-08-08 17:26:28 +02:00
.mailmap add .mailmap file for mapping git author name/mail in shortlog 2016-08-08 17:40:28 +00:00
AUTHORS move openbsc/* to repos root 2017-07-12 23:17:10 +00:00
COPYING move openbsc/* to repos root 2017-07-12 23:17:10 +00:00
Makefile.am contrib: remove rpm spec file 2024-05-08 14:41:07 +02:00
README.md README.md: Add links to forum + issue tracker 2024-03-23 12:47:12 +01:00
README.vty-tests update git URLs (git -> https; gitea) 2022-06-18 12:27:10 +02:00
TODO-RELEASE vlr: Use new libosmogsm struct osmo_gsup_pdp_info fields 2024-01-26 18:07:43 +00:00
configure.ac contrib: remove rpm spec file 2024-05-08 14:41:07 +02:00
git-version-gen git-version-gen: Don't check for .git directory 2018-07-24 18:05:46 +02:00
osmoappdesc.py osmoappdesc.py, tests: switch to python 3 2019-12-12 09:29:19 +00:00


osmo-msc - Osmocom MSC Implementation

This repository contains a C-language implementation of a GSM Mobile Switching Centre (MSC) for 2G (GSM) and 3G (UMTS). It is part of the Osmocom Open Source Mobile Communications project.

OsmoMSC exposes

  • A over IP towards BSCs (e.g. osmo-bsc: 3GPP AoIP or SCCPlite
  • IuCS over IP towards RNCs / HNBGW (e.g. osmo-hnbgw)
  • MGCP towards a co-located osmo-mgw for the RTP streams
  • GSUP (instead of 3GPP MAP) towards osmo-hlr
  • SMPP towards any external SMS sending/receiving applications
  • MNCC as external call-control interface towards e.g. osmo-sip-connectr
  • The Osmocom typical telnet VTY and CTRL interfaces.
  • The Osmocom typical statsd exporter.

OsmoMSC implements

  • mobility management
  • call control (either via built-in MNCC handler or external osmo-sip-connector)
  • voice group call (VGCS) and voice broadcast calls (VBS) as used in GSM-R
  • USSD (exposed via GSUP)
  • SMS (either via built-in SMSC or external via GSUP)


You can find the OsmoMSC home page and wiki online at https://osmocom.org/projects/osmomsc/wiki.

GIT Repository

You can clone from the official osmo-msc.git repository using

    git clone https://gitea.osmocom.org/cellular-infrastructure/osmo-msc

There is a web interface at https://gitea.osmocom.org/cellular-infrastructure/osmo-msc


User Manuals and VTY reference manuals are [optionally] built in PDF form as part of the build process.

Pre-rendered PDF version of the current "master" can be found at User Manual as well as the VTY Reference Manual


We welcome any osmo-msc related discussions in the Cellular Network Infrastructure -> 2G/3G CN section of the osmocom discourse (web based Forum).

Mailing List

Discussions related to osmo-msc are happening on the openbsc@lists.osmocom.org mailing list, please see https://lists.osmocom.org/mailman/listinfo/openbsc for subscription options and the list archive.

Please observe the Osmocom Mailing List Rules when posting.

Issue Tracker

We use the issue tracker of the osmo-msc project on osmocom.org for tracking the state of bug reports and feature requests. Feel free to submit any issues you may find, or help us out by resolving existing issues.


Our coding standards are described at https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards

We us a gerrit based patch submission/review process for managing contributions. Please see https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit for more details

The current patch queue for osmo-msc can be seen at https://gerrit.osmocom.org/#/q/project:osmo-msc+status:open


OsmoMSC originated from the OsmoNITB project, which started as a minimalistic all-in-one implementation of the GSM Network. In 2017, OsmoNITB had reached maturity and diversity (including M3UA SIGTRAN and 3G support in the form of IuCS and IuPS interfaces) that naturally lead to a separation of the all-in-one approach to fully independent separate programs as in typical GSM networks.

OsmoMSC was one of the parts split off from the old openbsc.git.