Issabel PBX - Unified Communications
VICIdial Contact Center Suite
Open source CSTA library
Unified Communications Server
Unified Communications System - PBX System
Proximus Forum 700 pbx dial number management
A Better PBX For Your Business
Enterprise telephony recording and retrieval system
Java VoIP/SIP PBX system (replaced by jfPBX)
vTiger Freeswitch PBX Integration
Respins of various open source PBX projects
CRM system based on vtiger, adapted to Polish companies.