hub.amSoftware by 3CLogic
8x8 Virtual Office - Use your iPhone, iPad or iPod touch to make and receive calls using your 8x8 Virtual Office phone...
Asterisk - An open source telephony switching and private branch exchange service for Linux.
Vocalcom - Vocalcom is a cloud-based contact center, omni-channel customer experience and sales acceleration technology provider.
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.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
FusionPBX - FusionPBX is an open source FreeSWITCH GUI.