Sprint on Tuesday announed the "All-in" plan - an $80 a month cellular phone plan that includes both service and smartphone device fees. The plan will offer unlimited talk, text and data at $60, plus $20 to lease phones such as the iPhone 6 and Samsung's Galaxy S6.

The No. 3 U.S. cellular operato has focused on offers such as cutting subscribers' bills in half to get them to switch from other carriers, doubling its data capacity and hand-delivery of new phones.

The shift from traditional two-year contracts of subsidized phones to offering monthly leasing plans alongside service fee has sparked a price war among Sprint and its rivals, T-Mobile US, AT&T and Verizon Communications.

The plan, which includes a one-time $36 activation fee, will roll out on Tuesday.