Have you tried 'pairing' your Mobile phone up with your car via Bluetooth on your mobile.
IIRC, (don't quote me on this), but i think that the bluetooth is simply an extension of your personal mobile phone, so when you go into bluetooth settings on your mobile, sitting in the car, and press 'search devices' the sterio make should come up.
On sellecting this, once your mobile phone rings you press the phone button on the car sterio which mutes the radio and the car speakers link up to your mobile, the small mic kicks in and you talk, hands free.
There is more to this, so try it, and if this works i'll give you some more info.
As i say, i may be miles off, but worth a go.