How to use Asterisk as a SIP gateway with digium TDM400P

Hey I am a newer in Asterisk. I want to use Asterisk as a SIP gateway with digium TDM400P card. Now Asterisk and Digium card are installed in one Linux machine. One Siemens PBX is connected through one FXO port of Digium card. I want to set up a call from SJphone in another machine to one telephone in the PBX through Asterisk. Does anyone know how to get it working? Thanx.

Setup an extension that sends the call through the Zap channel.