Trunk and extension registered in FreePBX, but only get busy signal

I’m using a fresh install of the 5.211.65 distro, but I"m having an unusual problem. My SIP phone shows as registered in FreePBX, as does my to trunk to CallCentric. When I try to dial out from my SIP phone, I always get a busy signal. However, CallCentric’s logs show the number was successfully dialed. I also can’t call in. If I register the SIP phone directly with CallCentric (i.e. bypassing FreePBX), everything works fine.

Though I’m experienced with computers, I am new to telephony. I would appreciate any suggestions for troubleshooting this problem.

Thanks!

You could perhaps start with :-

http://wiki.freepbx.org/dosearchsite.action?queryString=troubleshooting

Then post appropriate configs and logs of apparent failed calls.