The Gateway Pro BT is capable to work as a media player (Gateway music functions are active only) or just a phone module. In order to turn a main function OFF (phone or media), you need to use the DIP switches on the hardware.
There are 6 DIP switches on the bottom of the Gateway. The default setting is all switch OFF, because the car configuration is loaded from the car side harness (cable detect).
For disabling the phone part, DIP switch #5 needs to be turned ON. You can choose this if you want to keep the factory phone module of the car.
For disabling the media function (Gateway music menu) of the Gateway, you need to turn DIP switch #6 ON.
After changing the switches, you need to turn off the whole car with closed doors for 10 minutes to finalize this new setting.