I've got the Blackberry 8100 and it links with the car perfectly. Good sound and good reception at the other end plus all of the numbers from each contact in the phone book - very happy with it.
Don't buy for the voice activation though. Get about 30 mph and you need to get used to hearing "Pardon....."
Don't buy for the voice activation though. Get about 30 mph and you need to get used to hearing "Pardon....."