T-Mobile fined $48M over slowing 'unlimited' data plans

T-Mobile, the country's No. 3 wireless carrier, will pay $48 million for not clearly telling customers how "unlimited" data plans weren't really, well, unlimited.

The Federal Communications Commission said Wednesday that T-Mobile had a policy to slow down the speeds of customers who were the heaviest data users. But the agency said the company didn't let customers know what the data-use threshold was for triggering the lower speed.

The FCC said T-Mobile started doing a better job with disclosures in June 2015. The carrier now says in small print on its website that slower speeds may result for customers using more than 26 gigabytes a month if the network is...