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OsmoMSC is an implementation of the 3GPP MSC (Mobile Switching Centre)
network element. It implements the following core functionality within
the 2G (GSM) and 3G (UMTS) networks:
* mobility management
* call control (either via built-in MNCC handler or external osmo-sip-connector)
* USSD (exposed via GSUP)
* SMS (either via built-in SMSC or external via GSUP)
Historically, OsmoMSC originated from the OpenBSC project, which started
as a minimalistic all-in-one implementation of the GSM Network. In 2017,
OpenBSC 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. Before,
it was the libmsc part of the old OsmoNITB. Since a true A interface and
IuCS for 3G support is available, OsmoMSC exists only as a separate
- GSUP towards OsmoHLR (or a MAP proxy);
- A over IP towards a BSC (e.g. OsmoBSC);
- IuCS towards an RNC or HNB-GW (e.g. OsmoHNBGW) for 3G voice;
- MNCC (Mobile Network Call Control derived from GSM TS 04.07);
- SMPP 3.4 (Short Message Peer-to-Peer);
- The Osmocom typical telnet VTY and CTRL interfaces.
Find OsmoMSC issue tracker and wiki online at