Unified Communications Server
Java VoIP Softphone (SIP) (replaced by jfPhone)
High performance, production quality STUN server and client library
Accent interfaces and controls systems through goals and policies
Baresip is a modular SIP User-Agent with audio and video support
A Murmur-Server Webinterface written in PHP for Mumble
Optimized and cross platform SMPTE 2022 FEC library in C, Python, Java
C++ SIP stack based on Chrome source code