unxsVZ uSIPSwitch
uSipSwitch a micro sip switch (sip proxy) perfect for edge SIP SBC work (e.g. hosted PBX business). Comes with web console and DNS health tools. Uses modern clustering NoSQL technology for advanced HA.
Kamailio
Kamailio® (successor of former OpenSER and SER) is an open source SIP server released under GPL, able to handle thousands of c ...
FreeSWITCH
FreeSWITCH is a scalable open source cross-platform telephony platform designed to route and interconnect popular communicatio ...
opensips
OpenSIPS (Open SIP Server) is a mature Open Source implementation of a SIP server. OpenSIPS is more than a SIP proxy/router as ...
Yate - Yet Another Telephony Engine
Yate is a softswitch (concept of separating the network hardware from network software). It supports VoIP protocols: H.323, ...