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.
Issabel PBX - Unified Communications
VoIP SIP and SKINNY quality analyzer and packet / audio recording tool
Unified Communications Server
Matrix reference homeserver
A simple noise gate app intended for use with VOIPs like Skype.
Browse on Tor / i2p - Anon p2p Chat / FileTx, Conf / Video VoIP
H.323 Gatekeeper for VoIP and videconferencing
http://www.vaakpbx.com
Java wrapper for the popular chat & VOIP service
Free, native Windows SIP softphone with HD audio, SRTP encryption
Open source Fax server software for inbound / outbound internet Faxing
Respins of various open source PBX projects
High performance, production quality STUN server and client library
For more VoIP resources for business, take a look at the business VoIP category.