I have a ambulance being used for advertising purposes. The unit is complete with sirens and lightbars however I am attempting to change the sirens to different sounds such as ringtones found on cell phones. Does anyone have a suggestion on how this can be accomplished? The only thing I have thought of so far is to hook up a cd player with the tones and broadcast over the system. Problem there is I cannot select the tones as I desire (or the goof that is driving the rig).