AT&T said Tuesday that it has reached a deal to buy the Alltel U.S. wireless operations for about $780 million to boost its spectrum in rural areas.

The Dallas telecommunications company is buying the licenses, retail stores and network assets, along with about 585,000 subscribers, from Atlantic Tele-Network Inc. The news sent the Beverly, Massachusetts-based company’s shares up 9 percent to $42.74 in premarket trading.