AT&T will pay $60 million to resolve U.S. allegations it misled millions of smartphone customers by charging them for "unlimited" data plans but reducing data speeds if they used too much, the Federal Trade Commission (FTC) said on Wednesday.

As part of the settlement of the 2014 complaint, AT&T is also prohibited from making any representation about the speed or amount of its mobile data, without also disclosing any material restrictions on the data.