My understanding: Bluetooth is a "standard" that encompasses more than one service and many versions. Sometimes a connected device will tell you "connected for voice and music", and you may see two symbols on the display. So it sounds like they are two separate things, right? So the voice or phone service is monophonic (I think) and bi-directional and possibly doing things like dialing and caller ID. The music service is uni-directional stereo (most versions) and uses the connected device as a set of speakers. If you dig deep enough, you may find settings that let you turn these on or off independently. All of which may not directly affect the original subject of the post, but these things are computers trying to share data with each other in multiple formats with random versions. What could go wrong?