I am experiencing a problem with 3rd party sip phones (zoiper soft phone and ascom wifi), whereby the phones hit the required call-reject translation pattern when they dial 1234 and the call is blocked. However, no fast-busy tone is heard. Similarly, if call-precedence exceeded is selected, no audio is heard.
I think the solution is in a customized sip profile, but don't seem to have any luck. Calls to and from another extension are working fine.