Bluetooth specifies how to send data from one device to another, it doesn't specify what data to dens. So some phoned just don't connect to some car audio systems - especially if one of them is new, or has been updated, and the other is older or hasn't been updated. I don't think we'll see universal Bluetooth for at least a few years. (MMS used to be "same carrier only" - you couldn't send pictures to someone using a different carrier. It took about 5 years to get that straightened out.)