I have an iPhone 5 32GB on AT&T. They said about a week ago that I used 4.4GBs on my line alone. I reset the cellular data counter built into the iPhone and it says that I have used just over 1.5GBs and thats with adding the upload and download data usage together. Why does my iPhone say I used so little and AT&T say I used so much? Basically I am asking who is right? I use my phone for a lot of facebooking and twitter and just messing around while I am board at my job but I am not streaming a bunch of videos or downloading a bunch of apps.