Java VoIP Softphone (SIP) (replaced by jfPhone)
Accent interfaces and controls systems through goals and policies
SIP Video Multiconference Media Server with WebRTC support.
Open source streamlined SIP client built on Linphone
Optimized and cross platform SMPTE 2022 FEC library in C, Python, Java
The OZEKI VoIP Service Checker allows you to check VoIP services.
client-server full java chat audio-video file sharing
A suite of open-source tools and frameworks for creating SIP apps
C++ SIP stack based on Chrome source code