PJSIP is a free and open source multimedia communication library written
in C language implementing standard based protocols such as SIP, SDP,
RTP, STUN, TURN, and ICE. It combines signaling protocol (SIP) with rich
multimedia framework and NAT traversal functionality into high level API
that is portable and suitable for almost any type of systems ranging from
desktops, embedded systems, to mobile handsets.

This package includes patches from Ring project.