Crown Castle International said today it is paying $2.4 billion to lease and operate T-Mobile USA's 7,200 cell towers for the next 28 years.

The contract gives Crown Castle the option to buy the towers from T-Mobile for an additional $2.4 billion once the lease is up. 

“The T-Mobile assets are expected to provide significant growth driven by the continued demand for wireless data services, particularly in the most densely populated areas in the US,” Crown Castle President and CEO Ben Moreland said in a statement. 

T-Mobile plans to use the cash to pay off some of its debt, and help fund its $4 billion LTE rollout and network modernization project. It has agreed to rent the towers from Crown Castle for the next decade. 

T-Mobile has long sought a buyer for its towers to reduce its operating expenses, and most of the 51,000 cell sites comprising its nationwide network are leased from third parties. Rumors surfaced at the end of July that Crown Castle was the lead bidder for the towers still owned by T-Mobile. 

The transaction is expected to close during the fourth quarter of this year. After the deal closes, Crown Castle will operate about 30,000 cell sites in the United States and runs small cells in more than 50 markets. T-Mobile’s towers are concentrated in key U.S. markets, with 83 percent located in the country’s top 100 markets, Moreland said.

Crown Castle also controls 1,600 towers in Australia.

The agreement between the two companies was announced about a week after T-Mobile's new CEO, John Legere, took the helm. Legere succeeds former CEO Philipp Humm, who resigned in June.