No features have been listed yet.
FreeSWITCH - FreeSWITCH is an open-source media application designed to support popular protools such as SIP and WebRTC and provides a platform to develop voice and video applications.
Mitel - Business Communications and Collaboration
Asterisk - An open source telephony switching and private branch exchange service for Linux.
VoipSwitch - VoipSwitch provides complete VoIP and unified communications solutions.
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).
XO Hosted PBX - Hosted PBX is a scalable UC solution that uses cloud technology to integrate HD voice & data services, mobility, along with advanced calling