Hear who's Calling on BT Headset? WM5, Voyager 510

I want to be able to hear who's calling on my Bluetooth Headset.

I have a Windows Mobile 5 device (Cingular 8125) and a Voyager 510 Headset.
The Headset it paired both with my Desk phone and my Cell Phone.

I'm not sure the sequence of things, but I've heard the Cell Phone announce
the caller in the headset. I want this to happen all the time. How can I do
this??

Thanks,
Scott<-