Welcome to Kamailio (OpenSER) – the Open Source SIP Server


Kamailio (former OpenSER) 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), SIMPLE instant messaging and presence, ENUM, least cost routing, load balancing, routing fail-over, accounting, authentication and authorization against MySQL, Postgres, Oracle, Radius, LDAP, 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 Asteriskâ„¢, FreeSWITCHâ„¢ or SEMS.

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.