An IP Phone/CCM user dials an unallocated or disconnected PSTN number via MGCP or H.323. For various reasons, the gateway cannot/does not provide the caller outside dial-tone. CallManager receives the disconnect cause codes from the gateway, but since the call is not completely connected, there is no voice path established gateway. So the IP Phone plays a fast busy rather than the Telco error tones and message. The user never learns why the call failed.
Is there a way to have CallManager play or display the disconnect cause on the IP Phone?