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.
Bitrix24 - Bitrix24 is a free (for small businesses) social enterprise platform. It is a united work space which handles the many aspects of daily operations and tasks. Create your own social intranet in minutes!
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.
Autom8 Enterprise - Complete multi-channel cloud contact center solution
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).