We have a ccme 4.3(7.0) with 4 FXO, two of them connected directly to the PSTN, and the other ones connected to two cellfax analogue-GSM gateway (TelecomFM). We have problems with call disconnect in both connections, although the direct connection to the PSTN has been resolved configuring the next command:
supervisory disconnect dualtone mid-call.
But with the gsm gateway it doesn't work. When the remote peer ends the call, the cisco ip phone remains connected, and it receives a busy tone (or something like that) from the GSM gateway. When the cisco ip phone is forwarded to the voice mail, the message recorded includes this busy tone because the ccme continues the call as active, and the port is off-hook. What can we do to solve it?