I have done further testing. The onboard MGI on the MP20s works and I get voice both ways. It's only when I use the OAS card that it does not work. I have setup xlite to do a test call into the system using the OAS card and that works fine. I have also listened to an RTP trace when calling in/out using Gamma and I do hear the external party. So i'm not sure where the issue could be.