The Federal Communications Commission has been investigating AT&T’s supposed data throttling of its customers for years, and now its planning to slap the telecom with the single largest fine in FCC history. AT&T is being accused of purposely slowing down the network speed of certain users without properly informing them of how it all works, and now it may have to deal with a $100 million fine because of it.

Back in 2007, AT&T offered a number of unlimited wireless plans before it decided that wasn’t a good idea and shut the whole thing down 3 years later. Then, the company implemented a max bit rate cap on users that pulled down a set amount of data in a billing cycle, leaving them with speeds much slower than advertised, according to reports. The FCC claims the network would slow down so much that very basic mobile apps could not run properly. Basically, the FCC is saying once users with unlimited plans hit a certain cap, AT&T would just throttle them to the point where they could barely access the network until the billing cycle flipped over.

AT&T claims that it did disclose the network slow downs, but they were unfortunately set aside by the FCC. On the other side of the coin, the FCC says those disclosures were extremely vague and didn’t properly inform the company’s customers the way they should have.

As you can imagine, AT&T is upset and says none of this is true:

We will vigorously dispute the FCC's assertions. The FCC has specifically identified this practice as a legitimate and reasonable way to manage network resources for the benefit of all customers, and has known for years that all of the major carriers use it. We have been fully transparent with our customers, providing notice in multiple ways and going well beyond the FCC's disclosure requirements.