At the bottom of the second picture it tells you that the amount you see on the graph is measured by the device and that your carrier may measure data differently. So odds are that it could be including WiFi data on the phone graph.
Call at&t or check your account online to verify how much data has been used.
Sent from my GT-N8013 using Android Central Forums
The device doesn't add in wifi within the mobile data section. You can see wifi usage separately within the data usage section. Go into it and click the button on the bottom left (the menu button) and toggle show wifi. As you can see below after you toggle it the top shows mobile data and wifi data.
Michael the reason your data usage is different from your carrier is because of the bill cycle. Your text from att says your next cycle starts on the 20th but I can see in the data graph picture it says December 6th. So.. If we count a month from that the phones graph won't reset until January 6th. This means it's counting two different data billing cycles (not the entire thing but some).
Set your billing cycle correctly on the phone's graph and it will be alot more accurate. Not always perfect but from my own research its pretty close... As you can also see below my graph says I've used about 1.20 GB of usage. I go to Sprint and it says my 3g data is around 1.2 GB
.
Hope this helps!
Sent from my Sprint S3 using AC forums