T-Mobile CEO John Legere has announced that the U.S. carrier will begin taking action against customers with unlimited 4G LTE data plans that deliberately violate the company's terms and conditions by masking excessive tethering usage as smartphone data.

T-Mobile notes that less than 1% of customers are using apps or other methods to blow past their Smartphone Mobile HotSpot allotment, which is included free with every Simple Choice plan but capped at up to 7GB per month. The carrier says that, in some cases, these customers are using up to 2TB (2,000 GB) of data per month.

Here’s what’s happening: when customers buy our unlimited 4G LTE plan for their smartphones we include a fixed amount of LTE to be used for tethering (using the “Smartphone Mobile HotSpot” feature), at no extra cost, for the occasions when broadband may not be convenient or available. If customers hit that high-speed tethering limit, those tethering speeds slow down. If a customer needs more LTE tethering, they can add-on more. Simple. However, these violators are going out of their way with all kinds of workarounds to steal more LTE tethered data. They’re downloading apps that hide their tether usage, rooting their phones, writing code to mask their activity, etc. They are “hacking” the system to swipe high speed tethered data. These aren't naive amateurs; they are clever hackers who are willfully stealing for their own selfish gain.

T-Mobile says that customers who continue to have excessive tethering usage will first be warned, and then lose access to their unlimited 4G LTE smartphone data plan and be moved to an entry-level Simple Choice plan if they do not comply. T-Mobile began informing customers about the crackdown on network abusers today and has posted a detailed FAQ on its support forum.

T-Mobile prepaid and MetroPCS customers are not affected at this time.