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
Java VoIP/SIP PBX system (replaced by jfPBX)
Simple and efficient tool for SIP trace filtering
Baresip is a modular SIP User-Agent with audio and video support
This project has been relocated to http://github.com/sippy/rtpproxy h
Small and effective program for SIP traces anonymization
A suite of open-source tools and frameworks for creating SIP apps