DUN Profile (Dial Up Networking) is traditionally what you would look for on a phone to use your phone as a modem via BT. I'm not 100% on how everything works either, I was just pointing out that the two BT serial devices both work the same way. The one I ordered is cheaper and the first one has greater range, but both can be configured using AT commands, both take power from pin 9, etc. I have a friend with a Treo 650, let me experiment a bit with the adapter I ordered when I get it and I can tell you if it would be possible.