Sofia-SIP1.12.9

Sofia-SIP is an open-source SIP User-Agent library, compliant with the IETF RFC3261 specification. It can be used as a building block for SIP client software for uses such as VoIP, IM, and many other real-time and person-to-person communication services. Sofia-SIP is based on a SIP stack developed at the Nokia Research Center.

Sofia-SIP implementation follows RFC3261 and related key RFCs. Features such as early sessions, provisional responses, early media, caller preferences and session timers are included. Full set of transports, including both TCP and UDP over either IPv4 or IPv6, is supported. Signaling can be secured with SSL/TLS.

Sofia-SIP provides an implementation of the SDP offer-answer negotiation as specified in RFC3264. This is an essential component in using SIP to establish media sessions such as VoIP and video conferencing.