SIP Express Media Server

SEMS is a media and application server for SIP based VoIP services. It shows good performance doing basic services like announcements and conference for combination with external application servers, and, thanks to its easy to use and flexible application development framework and back-to-back user agent support, application logic and media serving can be combined in the same process. It can provide a full VoIP system together with SIP Express Router (SER), and has a flexible but powerful SBC (B2BUA) application included. Basic applications like announcement, pre-call announcement, RBT, conference, voicemail, mailbox etc. and lots of example applications available. Scripting in python and a simple state machine description language. Support for all commonly used free codecs (g711, gsm, iLBC, speex, adpcm, l16 etc), wideband, ZRTP encryption, SIP registrar client, XMLRPC server/client, DIAMETERi client and more.

SEMS is free software (speech+beer), it is licensed under dual license terms: the GPLv2+ and proprietary license.

Version 1.3.0
- SIP stack moved into the core (no need to load sipctrl any more)

- session app/signaling thread pool support (for very high session count)

- reduced memory usage if no RTP is processed

- SIP/UDP receive buffer configurable

- optimized potentially contentious mutexes

- multiple SIP/UDP receivers for even more signaling performance

- daemon mode can be compile-time disabled

- command line params may overrule config file

- CMake build with older versions possible (2.4)

- simple mode for voicemail/voicebox, usable without special handling by proxy

- RTP DTMF reception fixed (using RTP TS)

- support for DTMF sending/relaying on app level

- json-rpc (v2.0) module for interfacing (sync+async)

- 100rel (PRACK, RFC 3262) support

- open webconference rooms at startup

- DNS cache, support for load balancing on DNS SRV records

- new tutorials, DSM examples

- DSM state machine scripting platform
- #include scripts
- sys.popen to run external programs
- proper dialout support with ringing events, variables passed, auth etc.
- app selection and call preparation on in-mem DB (monitoring), with fallback
- System DSMs - executed DSM scripts unrelated to calls
- full conference support, with subgroups (mixed sidebars)
- mix in file into call or conference
- consistency checks on DSM scripts
- sets() for variable replacement
- raw SIP message processing
- arrays (also recursive) in DI action
- utils.add/sub
- prefix matching for test

- UPDATE support for Session Timer

- B2BUA with Session Timer (using UPDATE/re-INVITE with last SDP)

- SIP Session Timer for webconference, conference, dsm, ivr

- SIGHUP stops active calls, SIGUSR1/2 can be used by apps

- G.729 codec module (Intel IPP wrapper)