Today, June 14, 2010, marks five years since OpenSER project was announced. The announcement was done with the release of version 0.9.4 - the development portal hosted by SourceForge.net being created several days before: http://sourceforge.net/projects/openser/.
It started as fork of SIP Express Router (SER) branch 0.9.x, aiming to build an Open Source project that relies on community and encourages contributions. Over the years, it succeeded to build a stable and very attractive SIP server.
In 2008, under some claims of trademark infringement from an US company, OpenSER was renamed to Kamailio. In 2009, Kamailio received Best of Open Source Networking Software Award (BOSSIE'09) by InfoWorld magazine.
Kamailio and SER teams started to work together again from November 2008. As of January 2010, Kamailio v3.0.0 includes all features provided by SIP Express Router (SER), based on a joint effort of the two teams done under development portal http://sip-router.org.
These days, the two applications share the same source code, the difference is the database structure used to store subscriber profiles and routing rules.
Next major release, version 3.1.0 is scheduled for September 2010, bringing lot of new features, many for first time implemented in a SIP server.