[HELP] Anytbody Have Suggestions for Setting Up SIP Trunk?

Hi,

New to the board, relatively new to Asterisk. Am trying to use Asterisk@Home as a SIP proxy server with a trunk to a SIP provider. The endpoints are an e-MTA and a Nortel MCS5400 proxy server.

The e-MTA does not have the proper SDP for login directly to the 5400 (missing Owner Username and Session Name fields), but Asterisk seems to fill this info in, hence using it as an intermediary.

Anybody have ideas on where/what/how config info I should be setting?

sip trunk? Issit the same as IAX trunk? coz i know the steps in IAX.