Cingular Extend and internet access?

I have a Nokia 3360 phone, and live in MA. I can use my phone when I am in
MA as a wireless modem for my Visor prism, as well as accessing the internet
directly. However, I recently made a trip through NY, PA, and NJ, and in
those states (listed as the Cingular Extend network on my phone) I was
unable to use my phone to connect wirelessly. Manually dialing the phone
number of the ISP worked (as in the phone dialed, and I heard the whine of the modem on the other end)
and if I used my springport modem with the phone
number it worked. It was interesting to note that I also couldn't connect
directly to the web with my phone in those states (something I could do in
MA).

Does anyone know about the status of the Cingular network in those states? I
emailed Cingular, and they said it didn't work because the wireless cingular
network in those states wasn't configured (or something like that) to allow
surfing. But I am still not sure why my phone wouldn't work as a modem. Any
ideas?

Chris