My dad has a trailblazer. It's got the two antena's on the roof (one of XM-radio, other for on-star). He doesn't have or use either. That being said, every time you open the door and get into the vehicle a woman's voice comes over the speakers and says, "Phone Unavailable".
It would be awesome if somebody could let me know how to turn that off for him. He's mostly used to it but it still drives him nutts every now and then. I appreciate the help!