How do I get the Bluetooth on my new Treo to work on the Prius?

I have a 2004 Prius. My old phone was a Motorola. Now I have a shiny new Treo 700p (the older model) and the Bluetooth on the phone recognizes the Prius, but the Prius can't find the phone. What do I need to do about this? It is so much nicer to talk to the car than to the phone, and now the law says we must use "hands free" mode" in the car. Does anyone know what I need to do to get the car and phone to talk to each other?

Jean