Question: What message should a mobile station use to transmit DTMFs during a H.324 call, if it has attached the user connection for multimedia and an appropriate channel is available?
Option 1: H.245 UserInputIndication message
Option 2: H.225 RasMessage message
Option 3: SIP INFO message
Option 4: RTP DTMF payload message
Explanation: According to the specification, a mobile station supporting multimedia CAT during the alerting phase of a mobile originated multimedia call establishment should support transmission of DTMFs using the H.245 UserInputIndication message if it has attached the user connection for multimedia and an appropriate channel is available.