One thing to check is the codec being used. The default for voip dial peers is g.729. If CCM is expecting g.711 and there is no transcoder, the call will fail. You could try adding "codec g711ulaw" to the voip dial peer pointing at Callmanager. For outbound calls to use the FXO, you will need a route patter(s) in CCM as well as a dial peer(s) on the gateway, such as:
dial-peer voice 1 pots
destination-pattern 9T
port 0/0/0
Hope this helps. Please post your voice gateway config if you need further help.
Brandon