I had a hard time setting this up myself, and not everything is always the same everywhere in the settings.

For the username both WAP@CINGULARGPRS.COM and ISP@CINGULARGPRS.COM seem to be valid, but which works when or where I have no clue. I use WAP and it works fine for me.

Make sure you have it set to packet data on the connection.

As for the access point name, it MUST be wap.cingular (or whatever your phone's settings say, which I believe is this for everyone).

The dial up number I use is *99#, though sometimes a delay might be needed in the number depending on the phone I guess, which is why (I assume) there are many variations on this number.

The password is always CINGULAR1

For this post case matters.

I use the LG CU500, and in it I had to check the settings manually to come about some of these myself rather than listen to what many other websites had.

You might also want to make sure you have Bluetooth DUN enabled on your phone (consult the manual if you don't know how, or the Internet).

And of course with Cingular/AT&T you need to have the unlimited media plan.

Hope this helps and good luck.