Cisco FXO Gateway

I have a cisco 1760 router running IOS 12.4(17) which supports sip. I have a two port FXS card and a two port FXO card. I am running on AsteriskNow beta6. I have configured my FXS ports to register with the Asterisk server and these work.

My FXO ports will not work. Does anyone out there have a working example of how to get your FXO ports in a cisco router to work with asterisk?