The limit does not exist
Via AP: When smartphones first came on the market, telephone companies offered “unlimited” data plans cheaply in an effort to attract users. Back then, there were so few smartphones, and even fewer users who used more than a couple of gigabytes of data, that advertising these unlimited plans would mean a great many people would buy them without using much data at all. As smartphones became more ubiquitous and easier-to-use, though, the number of heavy users on unlimited plans rose to the point where they outnumbered regular users, and it was no longer profitable to sustain truly unlimited use. Then, AT&T did something incredibly boneheaded: they started capping data use for certain unlimited plans. In a textbook “do not do this” move, AT&T throttled the service for the top 5% of users, or slowed it down until phones were rendered nearly useless for anything other than calls and texts. This varied by area, too. The top 5% in New York City would be using a vastly different amount of data than the top 5% in Middle-of-Nowhere, Kansas. Many customers subsequently sued AT&T for false advertising. Rightfully so, because I can’t imagine “unlimited” to mean anything other than “not limited at all”. AT&T has since announced that it will be throttling data at 3GBs/month for all unlimited users, not just the top 5%, which brought up yet another problem: limited users pay $30/month for 3GB of data, the same as so-called “unlimited” plans. All in all, AT&T’s handling of the affair has been a major clusterwhoops.