The US telecommunications regulator said Wednesday it plans to fine AT&T $100 million after the company sharply slowed down data speeds to customers of its unlimited mobile data plans.
The Federal Communications Commission said the company misled millions of customers who subscribed to AT&T Mobility's unlimited data services.
The FCC alleged that AT&T "severely slowed down the data speeds for customers with unlimited data plans and that the company failed to adequately notify its customers that they could receive speeds slower than the normal network speeds AT&T advertised."
The company's tactics violated the 2010 Open Internet Transparency Rule by ratcheting down data transfer speeds to customers, the FCC said.
"Consumers deserve to get what they pay for," FCC Chairman Tom Wheeler said in a statement.
"The FCC will not stand idly by while consumers are deceived by misleading marketing materials and insufficient disclosure."
The announcement of the fine gives AT&T 30 days to contest it.
AT&T said it would fight the fine, saying it extensively warned customers in 2011 that some high-volume users would see their transfer speeds slowed.
It also argues that the FCC endorsed its speed management program several times.
“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," the company said.
"We have been fully transparent with our customers, providing notice in multiple ways and going well beyond the FCC's disclosure requirements."