AT&T said it is selling 235 communication towers to Global Tower Partners for an undisclosed amount.

The towers are located across 24 states throughout the United States, and it expands Global Tower Partners' coverage in urban locations. With over 3,000 towers in the U.S. market, the company offers outsourced wireless service to the likes of AT&T, Centennial Wireless, Cricket, MetroPCS, Sprint Nextel, T-Mobile, and Verizon Wireless. Global Tower Partners is the third-largest U.S. tower company behind American Tower and Crown Castle.

"We believe these locations are an excellent complement to our core owned tower portfolio and will assist our customers in addressing their future coverage needs," said Marc Ganzi, CEO of Global Tower Partners, in a statement.

The mobile operator did not comment on the transaction when contacted, and it did not say how many remaining towers it still holds. Even though AT&T had a successful third quarter, the move could be a cost-saving measure to handle a slumping economy.

For some carriers, selling cellular towers is a way to cut costs by having another company pay for the upkeep and maintenance of the facility. Sprint recently sold more than 3,000 of its towers that use Code-Division Multiple Access and Integrated Digital Enhanced Network technologies to TowerCo.

"By leasing rather than owning these network facilities, we can better focus on our core business of providing communication services to consumers, businesses, and government customers," said Bob Azzi, Sprint's senior VP of field engineering and operation. "Significantly, this transaction provides Sprint Nextel with additional liquidity which gives us greater flexibility in managing our company."