VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
Unified Communications Server
VoIP/SIP Autodialer
for Adium, Pidgin, Miranda and Telepathy IM Framework
Enterprise telephony recording and retrieval system
SIP softphone
Callflow Sequence Diagram Generator
Simple and efficient tool for SIP trace filtering
Java VoIP/SIP PBX system (replaced by jfPBX)
This project has been relocated to http://github.com/sippy/rtpproxy h
Small and effective program for SIP traces anonymization
Baresip is a modular SIP User-Agent with audio and video support
A suite of open-source tools and frameworks for creating SIP apps