Bluetooth Car Kits and audio from phone

[Desmo]

I'm looking at ways of taking the audio from my N70 and broadcasting it out on my car stereo. I was thinking of just using a cassette adaptor as the quality doesn't need to be that great when I thought about a bluetooth car kit.

Would the car kit allow any sound from the phone to be played over the unit? e.g. Music player or TomTom etc. Or will it only handle sound from calls?

 

[Desmo]

That Pioneer unit still only looks like it will act as a hands free phone though, whereas I want it to act like a headset. I can't really justify the cost of a new HU either for what I want.

I've had another idea that should work. Was thinking of grabbing an old bluetooth headset, taking it apart and connecting a 3.5mm jack to the speaker output. Should then act as a bluetooth passthrough to literally anything I want to connect it to