Thanks for your reply and I apologize for my late response. The site you sent me also solves another mysterious problem that just occurred. I.e., while driving between Kerrville and Fredericksburg we began getting incoming unsupported calls which couldn't be answered through the hands free system. In fact the steering wheel hangup button wouldn't shut it off, only the screen hangup icon. Then the cycle would start again, repeatedly. We noticed we were in a roaming area, which was mentioned as a problem for the A900 in the site you recommended.
As we are in the process of selecting a new cell phone and new service provider it would be very helpful to have access to the pertinent cell phone review sites, such as the one you recommended, in order to determine compatibility with Lexus BlueTooth. Does anyone know how to obtain such information?