I signed up with a new 800 provider called tollfreesipgateay located here: http://tollfreesipgateway.com/Home.html After receiving my confirmation e-mail (IP address is verified), I simply replaced my current provider from sip.denetron.com to IP:188.8.131.52. When dialing a toll free number, I receive: Call to 1877888XXXX@(Ln.10004@TollFree800) has failed. [ V4 184.108.40.206:5060 UDP target domain=unspecified mFlowKey=872 ] replied: 502 Bad Gateway; from IP:220.127.116.11:5060 Attempt to reach <sip:1877888XXXX3@192.168.1.125> failed. Reason: Server Failure Should I swap back in sip.denetron.com, or any number of other 800 providers, the calls will complete. Does anyone know what would cause this error? My installation does have my hard coded IP address, and my other providers work flawlessly.