I just bought the IS 250, and my wife and I also have a treo 650. The dealer tried to set hers up real quick but he couldnt do it. So I told him id do it when I got home. My wife is out of town with her phone but I set up my treo like it says in the manual, no problems. I havent updated the software on my phone for a while, and I know my wife has so maybe it could be software compatibility. But good luck!