Browse free open source VoIP software and projects below. Use the toggles on the left to filter open source VoIP software by OS, license, language, programming language, and project status.
Unified Communications Server
A suite of open-source tools and frameworks for creating SIP apps
Java VoIP Softphone (SIP) (replaced by jfPhone)
OpenSource Call Center and Dialer System
H.323 Gatekeeper for VoIP and videconferencing