16. The system as claimed in claim 11 wherein the control unit is for: determining the utterance type based on the travel context; and wherein the communication interface is for receiving the command phrase based on the utterance type.
16. The system as claimed in claim 11 wherein the control unit is for: determining the utterance type based on the travel context; and wherein the communication interface is for receiving the command phrase based on the utterance type. 18. The system as claimed in claim 16 wherein the control unit is for stopping a plurality of an interruptible prompt based on a propagation switch for controlling an extent of stopping the interruptible prompt.