Section: 5.5.7.2 Start DTMF response by the network
Content: Upon receiving the START DTMF message the network shall either: - convert the received digit into a DTMF tone which is applied toward the remote user, or - send the DTMF digit as an out-of-band message (see 3GPP TS 23.205[ Bearer-independent circuit-switched core network; Stage 2 ]  [96]) and return a START DTMF ACKNOWLEDGE message to the mobile station. This acknowledgement may be used in the mobile station to generate an indication as a feedback for a successful transmission. If the network cannot accept the START DTMF message a START DTMF REJECT message will be sent to the mobile station. Upon receipt of a START DTMF ACK message or a START DTMF REJECT message, the MS shall stop timer T336.