Hi All,
Trying to configure the VoIP
then try "Nokia S60 VoIP Release 2.0 Configuration Tutorial"

http://www.forum.nokia.com/info/sw.n..._0_en.pdf.html

If you need to understand VoIP call flow try

SIP/VoIP Call Flow Messages
at
http://www.forum.nokia.com/info/sw.n..._0_en.pdf.html