The Kamailio SIP Server Project – The Open Source SIP Server
Continuous Development Since 2001
SER-Kamailio - the project that shaped the evolution of open source real time communications
Powering Open Real Time Communications
SIP Load Balancer, IP Telephony Engine, Least Cost Routing, SIP Firewall, Edge Proxy, SBC, Registrar and Location Service, Instant Messaging and Presence, MSRP, WebRTC, IPv4-IPV6, IMS, VoLTE
Welcome To Kamailio – The Open Source SIP Server
Kamailio
(successor of former OpenSER and SER) is an Open Source SIP Server released under GPLv2+, able to handle thousands of call setups per second. Kamailio can be used to build large platforms for VoIP and realtime communications – presence, WebRTC, Instant messaging and other applications.  Moreover, it can be easily used for scaling up SIP-to-PSTN gateways, PBX systems or media servers like Asterisk™, FreeSWITCH™ or SEMS.
Among the powerful features: asynchronous TCP, UDP and SCTP, secure communication via TLS for VoIP (voice, video, text); WebSocket support for WebRTC; IPv4 and IPv6; SIMPLE instant messaging and presence with embedded XCAP server and MSRP relay; asynchronous operations; IMS extensions for VoLTE; 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; Json and XMLRPC control interface, SNMP monitoring.
~~ ECOSYSTEM EVENTS ~~
May 7-8, 2026
click for more details
February 18, 2026
Kamailio – New Major Version v6.1.0 Released
– with four new modules and important upgrades, among them: multi-threaded TLS processing mode, message apply changes for transaction branch processing, functions for SIPREC with RTPEngine, stronger hashing algorithms support. For the latest minor release in 6.1 series, check the download link in the right sidebar.
September 3, 2021 – 20 years of development
anniversary for Kamailio project
Kamailio World Conferences
1st edition
(Apr 16-17, 2013);
2nd edition
(Apr 2-4, 2014);
3rd edition
(May 27-29, 2015);
4th edition
(May 18-20, 2016);
5th edition
(May 8-10, 2017);
6th edition
(May 14-16, 2018);
7th edition
(May 6-8, 2019);
8th edition
(April 27-29, 2020)
Kamailio Developers Meetings
1st edition
(Sep 27-28, 2018);
2nd edition
(Nov 14-15, 2019)
December 20, 2012
– Kamailio – SER
integration process is completed
, the project will continue to use the name Kamailio
September 02, 2011
– 10 years SER Conference
Kamailio SIP Router at Google Summer of Code 2011
September 01, 2009
Kamailio awarded Best Open Source Networking Software 2009
November 04, 2008
– Kamailio (OpenSER) and SIP Express Router (SER) teamed up to integrate back their source trees, known as the SIP Router Project.
July 28, 2008
due to trademark issues, OpenSER was renamed to Kamailio
. Click
here to listen the new name jingle
June 14, 2005
OpenSER project is created
as a spin off of SIP Express Router (SER)
September 19, 2002
– SIP Express Router (SER) is
released as open source under GPLv2
September 2, 2001
SIP Express Router (SER) project is started
by FhG Fokus Research Institute, Berlin, Germany
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.
News
Kamailio v6.1.2 Released
April 22, 2026
Security Advisories: Core And Auth Module – April 7, 2026
April 8, 2026
Kamailio v5.8.8 Released
March 6, 2026
Kamailio v6.0.6 Released
March 5, 2026
Kamailio v6.1.1 Released
March 4, 2026
Kamailio v6.1.0 Released
February 18, 2026
Kamailio World 2026: Selection Of Speakers
February 16, 2026
DONATE TO KAMAILIO
Download latest release
6.1.2
(Apr 22, 2026)
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