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.

the library is implemented in ansi c, and provides an extensive set of features for implementing sip/simple user-agents. highlights include full udp/tcp/tls support, ipv4/6 support, simple presence and messaging support, sip offer/answer engine and numerous mechanisms for nat/fw traversal.

this package provides the main library runtime files.