I'm in the same boat. I purchased a Griffin BlueTrip to do A2DP Bluetooth music streaming since my vehicle only does Bluetooth handsfree calling. My wife's Android and a friend's iPhone can both select which profiles to use for a Bluetooth device, so they can choose to stream music to the BlueTrip and calling to the vehicle. Unfortunately, Windows Phone doesn't appear to support this, yet. I did manage to get my Lumia 920 to stream separately, they way I want, by pairing the vehicle after pairing the BlueTrip, but it was only temporary. As soon as I restarted the vehicle, the Lumia went back to connecting with the BlueTrip for both. It appears this is because the BlueTrip boots up faster than the vehicle's Bluetooth so the Lumia sees the BlueTrip first. Luckily, the BlueTrip does an adequate job of handsfree calling, so I'm okay for now. However, when compared, I've had callers tell me the vehicle handsfree is slightly clearer, so I hope Windows Phone adds the ability to select Bluetooth profiles per device.
01-07-2013 07:02 AM