This is the first time I have tried to connect Accessline SIP trunks to our 5000 system. This is the 4th provider I have tried. I was able to make them all work but not happy with the audio quality. Anyway I can call out on the trunks but cannot receive a call. The tech at Accessline says he sees a SIP error message 403 - Forbidden. I have tried setting the day ring-in type to single with an extension and tried a call routing table with the DID number pointed at an extension. Nothing works. Must have some other setting wrong. Any clues?

Craig,
Did you set "Use ITU-T E.164 phone number" flag to yes? This is under the configuration of the SIP trunk group. The ring it in to call routing with the appropriate patterns and destinations.

Thank you for the tip, but when I turned on the "Use ITU-T E.164 phone number" it broke the outbound calls. I discovered that it was a firewall problem. My SonicWall TZ 170 has a setting "Enable SIP transformations" which I had to enable to fix this problem.