AT&T agreed to pay $60 million on Tuesday to settle a Federal Trade Commission complaint that the company misled unlimited data plan customers when it slowed their speeds.

Driving the news: The $60 million will go into a fund that AT&T will use to provide partial refunds to both current and former customers who signed up for unlimited plans before 2011 and had their data speeds slowed by AT&T. The FTC said the carrier throttled the speeds of 3.5 million customers, per its complaint.

The settlement also requires the company to prominently disclose any future restrictions on speed or the amount of data within its mobile plans.

Background: AT&T faced complaints from both the FTC and the Federal Communications Commission. The agencies claim the company failed to adequately inform smartphone customers with unlimited data plans that, if they reached a certain amount of data use in a billing cycle, their speeds would be reduced to the point that many applications would be difficult to use.

The FTC filed its complaint in 2014, and won a victory at the 9th Circuit Court of Appeals when AT&T argued the agency lacked jurisdiction over the telecom company.

What they're saying:

Andrew Smith, director of the FTC's Consumer Protection Bureau, said AT&T failed to deliver on its promise of unlimited data. Democratic Commissioner Rohit Chopra, who supported the settlement, described the case as an example of how a dominant firm can cheat customers.

"AT&T baited subscribers with promises of unlimited data, trapped them in multi-year contracts with punishing termination fees, and then scammed them by choking off their access unless they moved to a more expensive plan," Chopra said in a statement.

An AT&T spokesperson said the company disagrees with Chopra's "baseless characterization" of the case. "None of his allegations were ever proved in court," AT&T said in a statement. "We were fully prepared to defend ourselves, but decided settling was in the best interests of consumers.”