Welcome to Kamailio® – the Open Source SIP Server

Kamailio® (successor of former OpenSER and SER) is an Open Source SIP Server released under GPL, able to handle thousands of call setups per second. Among features: asynchronous TCP, UDP and SCTP, secure communication via TLS for VoIP (voice, video); WebSocket support for WebRTC; IPv4 and IPv6; SIMPLE instant messaging and presence with embedded XCAP server and MSRP relay; asynchronous operations; IMS extensions; ENUM; DID and least cost routing; load balancing; routing fail-over; accounting, authentication and authorization; support for many backend systems such as MySQL, Postgres, Oracle, Radius, LDAP, Redis, Cassandra, MongoDB, Memcached; XMLRPC control interface, SNMP monitoring. It can be used to build large VoIP servicing platforms or to scale up SIP-to-PSTN gateways, PBX systems or media servers like Asterisk™, FreeSWITCH™ or SEMS. Kamailio and the SIP Express Router (SER) teamed up for the integration of the two applications and new development.

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  • October 16, 2014Kamailio (SER) – New Major Version v4.2.0 Released – with asynchronous event API, MongoDB connectors and lots of other new features. For the latest minor release in 4.2 series, check the download link in the right sidebar.
  • September 02, 2011 – 10 years SER Conference

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Kamailio Bossies'09

  • November 04, 2008 – Kamailio (OpenSER) and SIP Express Router (SER) teamed up to build the SIP Router project

The SIP  Router Project

Development site (SVN source code repository, bug tracker) is hosted since 2005 by SourceForge.net for Kamailio (OpenSER) 0.9.4 up to version 1.5.x, at:

Kamailio 3.0.0 and greater use since 2009 the SIP Router Project server to host the tracker and GIT source code repository:

Kamailio can be used on systems with limited resources as well as on carrier grade servers. It is written in pure C for Unix/Linux-like systems with architecture specific optimizations to offer high performances. Kamailio Project aims to be a collaborative environment of its users to develop secure and extensible SIP server to provide modern Unified Communication and VoIP services.