Recommended readings
Most of the documentation assumes you have a strong understanding of SIP. If you are coming from Asterisk or other software that requires little understanding of SIP, you are recommended to have a read through RFC3261 and read the documentation of the TM module thoroughly. RFC3261 is long, but it explains many of the concepts that are important to SIP such as Dialogs, and Transactions.
Other relevant RFCs
* RFC2327 Session Description Protocol * RFC2976 SIP INFO * RFC2833 DTMF in RTP * RFC3865 Presence
( this list is incomplete )
