T-Mobile's bombastic CEO John Legere does not mince words. Following an impromptu Periscope broadcast on Sunday, he's published an open letter on the T-Mobile website that lays out his plan to go after those dirty, rotten data thieves. You know the ones—people who use their unlimited data lines to get unlimited tethering data, bypassing the 7GB cap. Legere seems deadly serious about this, and there's a full FAQ detailing what Tmo is doing about it.

According to Legere, a very small segment of T-Mobile's user base is using apps and services to hide their tethering usage. That allows people on unlimited plans to get unlimited wireless hotspot data for connected devices, which is usually limited to 7GB per month. Legere says a few people are using upwards of 2TB per billing cycle this way. He alleges this has a negative impact on other customers, and T-Mobile has worked out a way to stop them.

T-Mobile claims to have a new network technology that can detect tethering activity that was previously obfuscated. Starting on August 31st (Monday), about 3,000 T-Mobile customers who have been heavily "abusing" unlimited data tethering will be contacted and warned. If they don't knock it off, they'll be forced onto a standard limited data plan, which will result in capped speeds after a certain amount of data regardless of how it's being used.

T-Mobile isn't going into detail about how it is detecting tethering use (it used to just check the useragent), but I'm sure someone's going to figure it out. Maybe there will be a workaround, then T-Mobile will make a change to block it, and so on. The cat and mouse game might never end. Whether or not it's true that unauthorized tethering screws up the experience for others, tethering to a computer or tablet definitely results in more data usage than on a phone. So, I suppose there's a valid argument for limiting it if resources are indeed constrained. Legere's concept of "stealing" data is... interesting, to say the least.