My understanding is that you cannot use a phone other than the MB phone. Apparently there is software built into the phone that permits the interface with the car -- handsfree, etc. When you turn the phone on, it says "Mercedes Benz", so there's obviously something more there than a plain vanilla Motorola Timeport. I suppose you could get an aftermarket hands free kit for any brand phone, but you will lose the voice activation, display of directory, etc. Same is true by the way for BMW built-ins.