I left the 2005 STS car motor running and went in the house to get something I forgot. While I was there my brother called me on my cell phone which was in my pocket. I was talking to him for a few minutes and then decided to walk back toward my car while continuing to talk. As I got 20 feet from the car the phone went dead and I heard my brother yelling "are you there" from the car speaker. Seems that when the phone transfer to blue-tooth, it shuts down cell phone speaker and microphone to avoid feedback.