I have a Zumo 550. I have it blue tooth enabled but I don't use the mike. I have the audio output routed to the aux input on my HK radio. I select aux on the radio and I hear everything through the speakers ( the GPS prompts, mp3 audio, Satellite radio and the Phone audio if I answer it using the touch screen.) I never answer it through the GPS but it's great knowing who is calling as that appears on the screen and I know if I need to pull over and call the person back. The Zumo 550 is the best GPS I ever had.