stayathomedad

Hi all,
I just bought a 2008 suburban ltz. No navigation, bose, rear entertainment, with onstar. I can't figure out how to pair my phone for bluetooth. I've tried hold the talk button on the wheel and it says onstar ready, but when I say bluetooth it does nothing. My phone won't find the car in search mode.
Do I need a onstar account or service?
any ideas or help would be appreciated