SIP

Session Initiation Protocol (SIP) :

  - FAQs, background materials and lists of current work in this field.
FirstHand Technologies :

- Client and server software developer for service providers and telecom equipment vendors, to address enterprise mobility markets.
IETF SIP Charter :

- Working group for protocol development. Links to RFC's and internet drafts.
PROTOS Test Suite :

- A test-suite to find vulnerabilities in protocol software.
pulver.com :

- A collection of information on the protocol. Contains news, reports and an IP telephony job noticeboard.
The SIP Center :

- Portal with technical and market resources aimed at commercial developers. Also provides a testbed area for software and proxy development.
SIP411 Directory Services :

- A Yellow Pages style directory of SIP addresses.
SIP Forum :

- A membership based forum. Also contains a news board.
SIP Made Easy :

- An introductory tutorial talks about protocol functions, components, message types, how it works and where it is applied.
SIP Wiki :

- Wiki based resource containing information and links.
SIPfoundry :

- An international open source community providing VoIP solutions and technology based on the SIP standard.
Soft Front :

- Provides a software development environment.
Tech Invite :

- Portal containing links to technical information and RFC documentation.
Vidosystem :

- Produces softphones. Site has downloads section and information on protocols supported.
Voice System :

- Design, consultancy and development for SIP Express Router (SER) servers.
VoIP User :

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