This is obviously aimed at those who jailbreak and use apps like MyWi vice paying for internet access at their homes. Jailbreaking is not a crime but AT&T sure as hell doesn't have to like it.
Even if they payed for the tethering plan they would still do it. These companies just don't want you to use the unlimited data like it's intended to be used. As much as you want. They don't want to spend more money to upgrade their network so they control what their customers can use.
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Just download less :/ use free open wifi more. I am sorry but some people must really abuse their downloads to go over some caps.
How about get what you pay for.