I got an iphone 4s two months ago and the first month, the bluetooth synced fine, phone calls worked as they always had in my gen II Prius. But about 3 weeks ago, although the 4S syncs, I can't answer it on screen anymore and the sound of the caller comes through the phone's internal speaker, not the car's speakers. Callers can't hear me at all unless I have the phone to my head which defeats the purpose of bluetooth. I tried re-pairing, no change. I am mystified as to why it suddenly quit working. Anyone else having this issue?