I have the HTC One, not locked to any carrier, running Sense. I can root the phone if required.
In my car, the cars built in BlueTooth (Alfa Romeo Blue&Me) supports phone calls but not audio streaming. In order to get streaming audio, I've connected an 'XLink' device to the CD Changer of the car, this allows me to stream Spotify. However, when I connect to the XLink, the phone kills the connection to the car.
Ideally I want the phone connected to the XLink for streaming music, but connecting to the car for incoming (and outgoing) calls.
Is there any applications or custom roms that would make this possible?