12. The system as claimed in claim 11 wherein the control unit is for stopping the interruptible prompt based on the command phrase matching the trigger phrase.
11. A content delivery system comprising: a control unit for determining an utterance type of either receiving a command phrase or setting up a trigger phrase based on a travel context; a communication interface, coupled to the control unit, for receiving the command phrase based on the utterance type according to the travel context; wherein the control unit is for: determining a trigger match based on the command phrase matching the trigger phrase representing a phrase for stopping a prompt, stopping the prompt according to a prompt type representing an interruptible prompt based on the trigger match, and continue playing the prompt representing the prompt type of an uninterruptible prompt even if the trigger phrase is detected for controlling the prompt presented by the device.