Communifire - Enterprise Social Collaboration Software
Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
DigitalChalk - Online Training Software and Learning Management System (LMS)
PhonerLite - PhonerLite enables your PC to use it for internet telephony (VoIP , Voice over IP, SIP).
Workplace by Facebook - Connect everyone in your company and turn ideas into action.
tSIP - tomeko.net/software: SIP client for Windows.