Commercial software development company that produces PBX, router, proxy and application server software.

Products for small to medium sized offices and a server database.

A proxy service provider with information in English and French.

Developers of a proxy server. Site contains downloads, documentation and a forum.

Applications developer. Products include software PBX's for enterprise and and service providers.

A USA based proxy service provider and supplier of hardware phones and routers. Site contains call rates and service details.

Sells off the shelf code and provides a software consultancy service.

News and reviews of hardware, software and service providers in the United States.

A test-suite to find vulnerabilities in protocol software.

A collection of information on the protocol. Contains news, reports and an IP telephony job noticeboard.

FAQs, background materials and lists of current work in this field.

A working group experimenting and documenting the protocol. Contains various internet technical resources.

A membership based forum. Also contains a news board.

A community with a modular framework of open-source applications for the development of SIP software.

Wiki based resource containing information and links.

A Yellow Pages style directory of SIP addresses.

A UK based service provider. Also contains hardware related links and protocol white-papers.

Software component developer for service providers and telecom equipment vendors.

Provides a development environment for software centered around SIP/VoIP technology.

Portal containing links to technical information and RFC documentation.

Portal with technical and market resources aimed at commercial developers. Also provides a testbed area for software and proxy development.

Design, consultancy and development for SIP Express Router (SER) servers.

Information on available technologies and software/hardware product reviews.

Consumer guide and forum. Also has software phone downloads and links to service providers.