Works but sound quality and microphone unconvincing

I can not connect fully the otherwise very positive criticism. The device works as advertised and is very easy to use. Pairing with my iphone 3 was done within seconds.
It turns on automatically when one rises to the phone in the car, but you always have to press a button.

However, the sound quality when making calls is not very good (the speaker rattles almost) and I have to understand problems and also my interlocutors complain that they hear me properly.
I have a Volvo XC90 and maybe it's because the sun visor before meinm head is wider than in other cars.

The FM function also works fine for listening to music with my iPhone.