from at&t website
We are the largest communications holding company in the world by revenue. Operating globally under the AT&T brand, we are:
Proud to offer one of the world's most advanced and powerful global backbone networks, carrying 23.7 petabytes of data traffic on an average business day to nearly every continent and country, with up to 99.999 percent reliability.
Ok so if data actually cost $10 per GB at&t would be spending $250 million a DAY( or $90 billion a year ) on data. We all know they don't.