Ameyo - Ameyo is a powerful and highly flexible IP-based contact center software that lets you have a personalized interaction with every customer across multiple channels, thereby driving customer engagement to a level par excellence.

freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).

Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs

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.

Five9 - Five9 provides cloud-based call center software for sales, marketing and support.

Asterisk - An open source telephony switching and private branch exchange service for Linux.