Of course, the peculiarities of the US phone market might impact whether a particular network will allow proper GPRS use, but I can't imagine it being that backward ;-)
Not true. Many different phones have worked with it. I have a nokia 6230 and a Motorola RAZR-- both work.
How did you get the 6230 to work? I just spoke with Nokia Support yesterday (after Level 3 T-Mobile support) and Nokia told me there is a known Bluetooth chip issue that will not allow bluetooth data transfers on the 6230.
I have unlimited Internet access working fine on the 6230 and the bluetooth pairs with the 770 but then I get a "Subscribe to GPRS" error on the 6230 and then a server error on the 770. Nokia told me I'd need to get the bluetooth chip swapped out in Florida but I plan on sending this 3-week old 6230 back to Amazon. I'd like to keep it if the bluetooth modem worked.