Issabel PBX - Unified Communications
VoIP/SIP PBX system (formerly known as jPBXlite)
VICIdial Contact Center Suite
The most affordable CRM system according to Capterra
Unified Communications Server
Unified Communications System - PBX System
Security tools that can be used to audit SIP based VoIP systems
This is a PBX dashboard showing the peer,queue,agent at real time
A Better PBX For Your Business
Enterprise telephony recording and retrieval system
ERP, IP PBX, Accounting, CRM, Time tracking, and etc.
Java VoIP/SIP PBX system (replaced by jfPBX)
Respins of various open source PBX projects