VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
VICIdial call center optimization tools, monitoring utilities, and per
ICTCore: Unified Communications Framework for web developers
Issabel PBX - Unified Communications
Unified Communications Server
Unified Communications System - PBX System
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
H.323 Gatekeeper for VoIP and videconferencing
Asterisk and kannel integration
SIP Video Multiconference Media Server with WebRTC support.
A command line utility for remote controlling Polycom VVX IP phones
Java VoIP/SIP PBX system (replaced by jfPBX)
An administration web interface for Mumble VoIP servers in PHP
Microscopic AGI framework.