Matrix reference homeserver
Issabel PBX - Unified Communications
VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
VICIdial call center optimization tools, monitoring utilities, and per
Unified Communications Server
Unified Communications System - PBX System
High performance, production quality STUN server and client library
Kazoo Live Medium. From Null to a Full Featured PBX on minutes
Accent interfaces and controls systems through goals and policies
Asterisk and kannel integration
H.323 Gatekeeper for VoIP and videconferencing
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)
Simple web interface for mapping CDR from VoIP provider to Asterisk
An administration web interface for Mumble VoIP servers in PHP