I ran into a similar problem with my ’99 E430 and I have resigned myself to not using the integrated cell phone. I found my MB "service advisor" knew very little. I got better info from a cell phone/stereo retailer. He told me the radio is designed to work with a particular model Motorola phone, and the phone installed is an old analog phone and analog is not supported by AT&T in my area. He said it would be difficult now to find a Motorola phone that is the same model but has the correct digital service that is supported by AT&T. So, the car radio only works with a particular phone model & you have to find the version of that model that will work with your cell provider’s system (THEY ARE ALL DIFFERENT!). If you must have the integrated system, you may be buying a new stereo and a new phone if MB has not changed the connections to all the other stuff; CD changer, speakers, etc. Good luck!