Thanks for all the replies but I finally got it working! Callcentric had been suggesting I used callcentric.com as the outbound proxy. I looked at the screenshot bigpapae35 provided and saw the outbound proxy set as srv.callcentric.com. I had tried this as recently as a few days ago but it did not work. But now for some reason it works. As soon as I typed it in and hit save my phone registered! So now that everything works Im wondering about all the settings Callcentric had me change. Here they are Does all this look ok?
Primary DNS: 184.108.40.206 Secondary DNS: 220.127.116.11 DNS Server Order: Manual DNS Query Mode: Sequential
Handle VIA received: Yes Insert VIA received: Yes Handle VIA rport: Yes Insert VIA rport: Yes Send Resp To Src Port: Yes