http://www.tech-invite.com/ a Portal devoted to SIP and surrounding technologies
The Web site is primarily based on the standardization work carried out at the IETF. Its purpose is to contribute to the promotion and knowledge of SIP and surrounding technologies. It references all the drafts (including the individual ones) and RFCs for all the IETF working groups belonging to the RAI (Real-time Applications & Infrastructure) area as well as the Security area. Some other working groups or some other drafts and RFCs are also referenced as "miscellaneous". This represents more than 40 IETF working groups. TISPAN NGN and 3GPP specifications (not only for IMS) are also covered. Numerous examples referred to in these documents are illustrated and comprehensive ABNF grammars related to SIP, SDP and some other protocols are available.
