I have a bluetooth 1.2, hfp1.0, hsp1.1 compatible car audio (LG LAC8600R). I tried 3 Nokia phones:
6310 (bluetooth 1.1, hfp1.0, hsp1.1)
6230 (bluetooth 1.1, hfp1.0, hsp1.1)
N73 (bluetooth 2.0, hfp1.0, hsp1.1), all of them worked well with the car audio (pairing, dialing, call receive, talking).
However, my phone Nokia 6233 with formware 5.10 (descendant of 6230) does not work. It is bluetooth 2.0, hfp1.5, hsp1.1. It pairs with the car audio, but does not connect calls, it always disconnects bluetooth connections when I try to take the call.
Is it a software bug in 6233, or handsfree 1.5 is not compatible with handsfree 1.0 at all?