Caller is able to recieve calls but unable to make calls, when making a call they get a flat dial tone.
Traces show the following:
Dec 20 10:51:51.676: ISDN Se0/0/0:15 Q931: RX <- DISCONNECT pd = 8 callref = 0x
Cause i = 0x829F – Normal, unspecified
The Cause code 82 is related to the receiving equipment (telco switch) requesting to use a channel that is not activated on the interface for calls.
This looks like an issue with BT who have deactivated the line (in this case, due to not paying bills)