1815-01: DTMF Relay [System: > VoIP: > Profile (1-4): > DTMF (1815):

DTMF Relay allows a VoIP extension user to dial DTMF digits to control a remote voice mail or other interactive service. If enabled for the selected profile, user-dialed digits are included as port of the transmitted voice packet, separated out at the far end, and then sent to the destination as in-band DTMF digits. If disabled, DTMF digits are not passed to the far end.