 SO let me save you some heartache. Here's the output from debug ccsip messages showing the failed call "Troubleshooting" on page 567 for more information): Feb 3 19:07:35.084: //-1/xxxxxxxxxxxx/SIP/Msg/ccsipDisplayMsg: Sent: SIP/2.0 404 Not Found Via: SIP/2.0/UDP 208.73.146.95:5060;branch=z9hG4bK6gmsg8300gk1vmsmj4g0.1 From: "DONAHUE GARY " <sip:+19735551212@192.168.101.113:5060>;tag=gK0a3f2f72 To:<sip:9735554333@192.168.101.100:5060>;tag=3DF80A8-23C0 Date: Thu, 03 Feb 2011 19:07:35 GMT Call-ID: pcst129676005500836719310@192.168.201.113 CSeq: 1 INVITE Allow-Events: telephone-event Server: Cisco-SIPGateway/I0S-12.x Reason: Q.850;cause=1 Content-Length: 0 Clearly, the SIP trunk is registered and the SIP INVITE made it to our router, but the provider still tells callers that our number is unavailable. The problem is that we have no ephone-DNs configured with the phone number. If we added the following ephone- DN and applied it to a phone button, the calls would ring on that phone: Small-Office VolP Example ephone-dn 22 dual-line number 9735554333 no-reg primary label SIP-Line-1 name SIP-Line-1 I didn't want to do this, for a couple of reasons. First, since this is a small office with only a few extensions, I'd prefer to have all the phones show only extension numbers and not the actual outside phone number. Second, since the phone number doesn't match my rudimentary dial plan (all my extensions are 1xx), if I create a generic voice mailbox for the outside line, the message indicator lights won't work. Again, there are almost limitless ways to accomplish this. You may pre- fer to have a button with your actual phone number attached. That's fine, and I encourage you to play around with such a config. Also, if we used the secondary number example shown previously, the SIP calls would have rung on that configured extension. Instead of adding a new ephone-DN for the SIP trunks, I've created a new extension for each: ephone-dn 32 dual-line number 132 no-reg primary label SIP-4332 call-forward busy 222 call-forward noan 22