John Legere, CEO of T-Mobile US
Controversial T-Mobile US CEO John Legere wants to go after data thieves using up to 2 terabytes of tethered LTE data a monthGetty Images

T-Mobile US CEO John Legere has announced that the mobile network will be actively pursuing subscribers that abuse 'unlimited' 4G LTE pans to steal huge amounts of tethered data.

T-Mobile, which is owned by Deutsche Telekom, is the third biggest mobile operator in the US with 59 million subscribers. One of the network's biggest selling points is that it offers an unlimited 4G LTE data plan with an included Smartphone Mobile HotSpot feature that lets users tether their mobile internet so that they can go online in locations where broadband is not available.

If subscribers use up their limit for high-speed 4G LTE data tethering, the speeds slow down, and if they use up their allocated data allowance, they can pay for some more. However, it seems that 5,900 users – less than 1/100 of 1% of all subscribers – have found a way to steal tethered LTE data and are each using up to 2 terabytes of data a month.

Data being stolen for nefarious purposes?

"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 e.t.c," Legere wrote in an open letter to T-Mobile customers.

"They are 'hacking' the system to swipe high speed tethered data. These aren't naive amateurs; they are clever hackers who are wilfully stealing for their own selfish gain."

"I'm not sure what they are doing with it – stealing wireless access for their entire business, powering a small cloud service, providing broadband to a small city, mining for bitcoin – but I really don't care!" wrote Legere, which seems to suggest that he suspects the stolen data could be being used for criminal purposes.

People often argue that unlimited plans should be well, unlimited, and therefore mobile operators should not be allowed to throttle the amount of data users consume, and Legere has previously promised that "when you buy data, that data is yours".

However, he argues that abusing the network has gone way beyond the pale and affects the user experience for everyone else.

No more Mr Nice Guy

"We are going after every thief, and I am starting with the 3,000 users who know exactly what they are doing. The offenders start hearing from us tomorrow. No more abuse and no risk to the rest of our customers' experience. It's over," wrote Legere.

"I'm not in this business to play data cop, but we started this wireless revolution to change the industry for good and to fight for consumers. I won't let a few thieves ruin things for anyone else. We're going to lead from the front on this, just like we always do. Count on it!"

Legere, who is often seen wearing a bright pink t-shirt, a black leather jacket and pink sneakers, is well known for making controversial remarks and swearing in the media and on Twitter, in what is seen as a "no bullshit" style of marketing to customers.

However, in June he was roundly criticised for using the term "rape" to describe the practices of T-Mobile competitors Verizon and AT&T at a company event.

"These high and mighty duopolists that are raping you for every penny you have, if they could do something nice for you they would," he said on stage at Seattle's Paramount Theatre. "The f@#kers hate you."