I have a number of issues with my N900 bluetooth connecting to my car kit (as do quite a few other people from looking through the forum and bugzilla) so I've been trying to look into it in the hope of finding some kind of solution.

Looking at recorded logs of the failed connections from syslog / bluetoothd it looks to me (as a complete beginner to this subject who has no understanding of the workings of bluetooth) like the car kit is sending pretty standard messages all of which are as listed in the Nokia document AT command set for Nokia GSM products. The only wrong looking message looks like an <AT+CSCS="GSM"> that is received from the car kit which although listed in the Nokia document is not understood by my phone.

Does anyone have any idea whether it is possible to modify any of the workings of the bluetooth system on the phone or is this all proprietary?