The Federal Trade Commission has accused wireless carrier T-Mobile of adding phony charges totaling "hundreds of millions of dollars" on customers' accounts without their consent.

USA Today is reporting at least as far back as 2009 until at least December 2013, T-Mobile placed unauthorized charges on customers' mobile phone bills for premium subscriptions. The suit filed was filed Tuesday in U.S. District Court.

The agency says T-Mobile participated in "cramming," a practice where the carrier places charges for services from a third-party company on consumers' bill without telling them.

The FTC adds that T-Mobile made it extremely tough for its customers to notice the charges.