The solution: The BT adapter!
The Bluetooth adapter can be set up in a few seconds on the phone, while the coupling is retained even when de-energized state. Once the USB adapter gets power through the vehicle, the adapter attempts to connect automatically and in several attempts by phone. The launch of the adapter and the successful pairing with the phone is output through the car speakers in soft tones.
The Bluetooth adapter this only signals the A2DP protocol and support, this gadget is ideal for music streaming.
Conclusion: Anyone who wants to use his car to the hands-free function and ONLY want to have an adapter for the music streaming, which is with this adapter on the correct page. I can easily connect my Windows Phone with a car and the BT adapter simultaneously and use the corresponding functions comfortable. The AUX cable falls quite short from 10-15 cm.