Inbound calls from CBeyond fail intermittently

I’ve converted an existing Asterisk 1.4.19 to AsteriskNow (the customer wants the GUI).

Everything works as before except that inbound calls from CBeyond fail. During the failure period, inbound calls from Teliax are successful.

The failure period begins, I think, following a reload. Either a GUI reload or a CLI reload can cause the problem. The failure period ends 15-30 minutes later for no apparent reason.

CBeyond say they are receiving a 404 during the failure period. In the logs, there is a message about user ‘’ (empty quotes) calling the DID number but the number doesn’t exist.

Does this make any sense to anyone?