If my previous suggestion does not work then I can only assume that there is a compatability problem, I believe there is a list somewhere of compantable phones but newer models should work with most wavebands...

Do you have a pairing button in the armrest? If so I would suggest putting the phone in there and giving it a try, thats what it said in my BMW telephone booklet (It also said that the range is limited) Give it a try you don't have anything to lose...

EDIT:

The other reason is maybe the bluetooth is compatable but the phone isn't, I have heard of this before... When I use my phone the headphones come on my phone like I am using a bluetooth dongle device, is a bluetooth dongle device compatable with your phone?