I recently switched from T-mobile to Att. I have the Skyrocket and when I was with T-mobile I had the Galaxy SII (same phone). I use my phone now the same way I did with Tmobile and my data seems to be adding up much faster. I'm over a gb in the middle of the month and on pace to go over 2gb easily. Does ATT do something different than other carriers as far as calculating data is?