https://consumerist.com/2017/09/20/t-mobile-raises-limit-for-unlimited-data/

Savvy mobile data users know that “unlimited” does have its limits: Plans that promise unlimited data are selling only theoretically unlimited data. That’s because all carriers reserve the right to drastically cut users’ connection speed to 2G or 3G if they go over this semi-invisible limit. Now T-Mobile is raising this threshold for its for its customers, from 32 GB to 50 GB.

The practice of cutting users’ connections down to a trickle of data once the carrier decides that they’ve downloaded enough is called throttling, and it’s a common one. But T-Mobile claims its system isn’t throttling: Big Magenta practices prioritization.