How cellphone carriers learned to stop worrying and love unlimited data

They've raised prices. They've slowed speeds. But despite their best efforts, the country's biggest cellphone carriers have been unable to kill off the unlimited data plan. Now they're discovering something else: Unlimited data is extremely popular. And it might just be the thing that saves them in an increasingly cutthroat market for wireless services.

After years of trying to shift customers to plans with monthly data caps, companies such as AT&T and Verizon have begun heaping praise on their newest unlimited data plans as consumers have flocked to them. The plans were once common in the industry. But telecom giants stopped selling them as consumer demand for data grew. Many unlimited customers found themselves signing onto metered plans when prices rose, or abandoning their unlimited plans after running into speed limits. Eventually, the number of those on grandfathered unlimited plans dwindled to a handful. In 2015, just 1 percent of Verizon's customers were on unlimited plans.