Beginning on Monday, T-Mobile USA will start taking action against people spoofing the carrier's network to "steal" unlimited tethering data, according to a blog post by CEO John Legere.
The people in question are using apps, rooting, and/or their own code to mask whether they're tethering phones to other devices, Legere said. Only a hundredth of a percent of T-Mobile's customers are allegedly involved, but some of them are claimed to be using up to 2 terabytes of data per month.
Like other major U.S. carriers, T-Mobile provides a small default amount of LTE tethering each month. Once that cap is hit the company throttles backs tethering speeds substantially until the next month, or a person pays for more data.
The crackdown will begin with about 3,000 subscribers "who know exactly what they are doing," Legere stated. An official FAQ notes that the company has developed technology to detect spoofers, and that anyone caught will first be warned and then risk having their smartphone plan downgraded from the unlimited tier to a capped one.
Legere also suggested that the issue is separate from complaints that it and other carriers have been misleading in promising unlimited smartphone data. In practice, U.S. carriers have generally imposed "soft" limits mentioned only in fine print. This June, the Federal Communications Commission levied a $100 million fine against AT&T for failing to adequately inform customers.