where can I get more document about sip?

I'm developping sip application, but where can i get more document about sip?
Please give me a link (detail link, not only foum.nokia.com)
or Send docments to my email: [email]mathlll@163.com[/email]
Thanks very much!!!!!!!!!!!!

I can only get the doc about SIPEx (The S60 3rd, SIPExample),
I need more, ,,,,,,,,,,,,,,,

Hi ,
Please refer the below link ,

[url]http://newlc.com/Using-SIP-with-Nokia-Series60-and.html[/url]

Regards,
Parag Purkar

1. [url]http://www.ietf.org/html.charters/sip-charter.html[/url]
2. [url]http://www.voip-info.org/wiki-SIP[/url]
3. [url]http://www.protocols.com/pbook/VoIPFamily.htm#SIP[/url]
4. [url]http://www.google.fi/search?hl=fi&client=firefox-a&channel=s&rls=org.mozilla%3Afi%3Aofficial&hs=zVd&q=SIP+protocol&btnG=Hae&meta=[/url]