KAMAILIO (OpenSER) is a mature and flexible open source SIP server (RFC3261). It can be used on systems with limitted resources as well as on carrier grade servers, scaling to up to thousands call setups per second. It is written in pure C for Unix/Linux-like systems with architecture specific optimizations to offer high performances. It is customizable, being able to feature as fast load balancer; SIP server flavours: registrar, location server, proxy server, redirect server; gateway to SMS/XMPP; or advanced VoIP application server.

KAMAILIO (OpenSER) aims to be a collaborative project of its users to develop secure and extensible SIP server to provide modern VoIP services. Anyone can contribute to one of next items:
- code development - KAMAILIO (OpenSER) core, modules and adjacent applications
- documentation - writing or enriching documentation
- miscellaneous - different management tasks (e.g., web site maintenance)
- ideas - new ideas bring brilliant solutions

Basic rules for contributions and the list of contributions you can read in this page .

Get involved:

• users @ lists.kamailio.org - KAMAILIO(OpenSER) users mailing list.
• devel @ lists.kamailio.org - KAMAILIO(OpenSER) developement mailing list.
• business @ lists.kamailio.org - KAMAILIO(OpenSER)/VoIP business related forum - see rules here.
• http://www.voipuser.org/forum_view_24.html - KAMAILIO (OpenSER) public web forum.
• http://voip-info.org/wiki/view/OpenSER - VoIP-Info.org page

KAMAILIO(OpenSER) can be:

• SIP proxy server
• SIP registrar server
• SIP location server
• SIP application server
• SIP dispatcher server
  
• full capabilities list is available in features page

KAMAILIO (OpenSER) cannot be:

• SIP phone
• media server
• back-to-back user agent
  

Resources:

- OpenSER History
- OpenSER News
- OpenSER Download  
- OpenSER Documentation