iPhone rang over car speakers???

[liquidsmoke]

well since you do have onstar, that has bluetooth and that is the method for voice calls, not via the pdim. There are 2 bluetooth chips in the car if you have onstar and the pdim.
if you've never paired your phone to the car, it could of just been a glitch. I wouldn't worry about it much unless its a consistent problem.
Ive had this happen before, but it was always because of me manually switching from bluetooth to the handset while it was connected. It seems it remembers how you last connected and prefers that over whats available, but will still ring on the car speaker till you answer the phone. This is more of a feature either with the onstar chip, the iphone or just in general how bluetooth works.