Two-year contracts are disappearing from the U.S. wireless industry.

Sprint Corp. said Monday it plans to do away with two-year contracts and will shift entirely to a model where customers lease their smartphones. Earlier this month, Verizon Communications Inc. said it would no longer sell contracts, and T-Mobile US Inc. did away with contracts more than two years ago. AT&T Inc. is the only major U.S. carrier that still offers to subsidize new smartphone purchases.

Two-year contracts had been the norm for years, in which customers signed the agreement in exchange for a discounted price on a phone. Now, carriers primarily offer cheaper monthly plans without contracts, but require customers to pay full price for their devices, typically in monthly installments spread out over two years.

Sprint began offering a lease option last year, and in an interview Monday, Sprint Chief Executive Marcelo Claure said the carrier will move entirely to that model by the end of the year. That means paying full price or leasing will be the only ways to acquire a new phone from the carrier. Sprint says 51% of customers who purchased a new phone last quarter used its lease option.

The wireless carrier, which has been struggling to retain customers and add new users, is now the No. 4 U.S. operator in terms of subscribers after falling behind T-Mobile. Earlier this month, Sprint said it ended the June 30 quarter with 57.7 million total connections while T-Mobile had 58.9 million.