I've been using my Sprint PCS Vision account over bluetooth dial up networking from a Palm TX without getting charged extra. But then, I am not using that much data. Apparently, Sprint doesn't know if you are using BT DUN or not, their system can't tell, it only knows the raw amount of data you use. So if you are using a ton of data, they'll probably suspect something and send you a nasty letter. Now, the new EVDO network knows wheter you are using DUN, so that will be interesting to see what happens. Hopefully the 770 will work over the CDMA network!