LAS VEGAS — A tug of war has broken out among the major wireless carriers.

As Americans rely more on their mobile devices, guzzling data along the way, the carriers are aggressively wooing new customers.

In perhaps the most daring move yet, T-Mobile US, the country’s No. 4 carrier, announced on Wednesday that it would cover the termination fees for individuals as well as up to five lines per family for consumers who leave their carrier. Customers can receive up to $650 in credit after trading in their phone.

It is the latest in a series of moves the company has made to gain customers, helping T-Mobile stand out among competitors whose offerings have largely remained the same — two-year contracts, complex family plans and stiff early-termination fees.

The industry is “just broken,” John Legere, T-Mobile’s chief executive, said at a news conference on Wednesday. He added: “What we are going to do is force the industry to get healthier.”