MetaDirectory
- Applied Voice & Speech Technologies, Inc. (AVST)
Applied Voice and Speech Technologies, Inc. (AVST) offers SIP integrations to its flagship CallXpress unified communications platform.
- BaseVoice
Commercial software development company that produces PBX, router, proxy and application server software.
- Brekeke Software, Inc.
VoIP telephony server software manufacturer. Includes product information, free download trials, and details of the support available.
- 3CX
Developers of IP PBX software for Windows.
- Interactive Intelligence: Interaction SIP Proxy
Site contains downloads, documentation and a forum.
- OpenSER
A branch of the SIP Express Router project, offering an open-source SIP server.