It's called "data throttling," the move AT&T made back in late 2011 when changing up its data plans. It turns out that "unlimited data plans" aren't that unlimited, despite their high costs. With data throttling, the provider waits until customers have reached a certain amount of data use per month, then places slowdowns and checks on the plan.
This means, when hitting up the last video or trying to send out a large file to friends, the throttling will make data move so slowly it won't even be worth it. No surprise - this made a lot of customers very angry. AT&T didn't really specify when it would start throttling data, and customers were seeing the effects after only 2GB of data use, which doesn't allow for many YouTube clips or mobile web surfing. As a result, people were paying more for an unlimited plan, but get throttled before cheaper 3GB max plans were even affected.
At last AT&T has responded to all the hate by coming out with some clear rules. The throttling cap is 3GB for HSPA+ and 5 GB for LTE services, better in both cases than the 2 GB problems.
The company pinky-swears that data throttling is only a band-aid fix while it works on better network capacity and infrastructure, but now that they've started, will they ever want to stop? Data throttling only affects about 5 percent of data users - in theory. But these are old numbers even now, a few months later. As data use continues to rise, everyone will be soon affected by these throttling rules.
Now that the company has apologized and set some real limits, customers should keep a close eye on the caps to make sure they move up, evolving along with data use itself. In the world of data, the word "unlimited" is moving from being an endangered species to a woolly mammoth.