I am using an 8 port digium 1a8b04f card 4 fxs ports and 4 fxo ports. I am able to make inbound and internal calls with no problems. If I connect a standard phone directly to the line I can make an outbound call. So the line is working. When I try to make an outbound call it just rings.
You need to provide a call-trace of a failed call, there are any number of things you might have not got right yet.