I have the following problem phone is A is set to Call forward All to Phone B.
When an internal call is made to phone A this is forwarded to phone B and if phone B is busy on a call then a engaged/busy tone is heard, this is the correct response.
However if a external call is made to Phone A via the PSTN and phone B is on a call then instead of receiving a engaged/busy tone, a number unobtainable message is heard and the call is cut-off
This is a CCM 5
Any suggestions to this problem would be greatly appriciated.