Shoutbox

There are two ways this can work.  What you are using is GPRS or EDGE service from the mobile provider.

The idea in your initial post, of calling a dialup ISP, also works.  If you do that, there won't be per-megabyte charges, just what it would normaly cost you to make the call (in money or plan minutes) -- however, you need a dialup account, and this kind of connection will be slower and less reliable than GPRS.

I occasionally use the dialup method, which for me works out free -- I have a dialup account from work and plenty of unused call time on my voice plan.