I just got a 2007 Toyota Sienna with Navigation and Bluetooth. I also have a Treo 650 (Sprint). What I'd like to do is use the Car Bluetooth when I am alone in the car, but have the option to use the headset when I have someone with me. The Car BT pairs with the 650 every time I get in the car, no issues so far. I can send the call back to the phone, which I have in a Seido Cradle. However I can't figure out how to get the call to my Plantronics 510. I have tried to use the combo button on the headset, which will usually pick up a call when not connected, but not while the car bluetooth is working. There doesn't seem to be a way to shut off the bluetooth short of deleting the profile, which would mean I would have to re pair the phone every time.