The most affordable CRM system according to Capterra
Unified Communications Server
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)
VozBox. Asterisk VoIP PBX.
CRM system based on vtiger, adapted to Polish companies.