VICIdial Contact Center Suite
Display incomming calls on your desktop
Desktop communication tool: chat, telephony, multimedia
ICTCore: Unified Communications Framework for web developers
Unified Communications System - PBX System
High performance, production quality STUN server and client library
Kazoo Live Medium. From Null to a Full Featured PBX on minutes
Blocks unwanted calls using caller ID and a modem
H.323 Gatekeeper for VoIP and videconferencing
OpenSource Call Center and Dialer System
C++ SIP stack based on Chrome source code