[calebu2]

Does this idea exist in software form? If not, is it theoretically possible?

I want to use my Treo 700wx as a control center for other bluetooth enabled phone devices (Currently I only have one other phone, but that could increase).

When a call comes through on the other devices, the treo provides the details and allows you to pick up and answer the calls.

If I want to make a call on another phone (e.g. because I get free international minutes on another phone), I can do it from my Treo using the Treo address book.

Oh, and if I am using a Bluetooth headset with the Treo, the call gets forwarded through to that.