Verizon Communications Inc., the second-largest U.S. phone company, said yesterday that it may sell its yellow pages unit, a deal that could be worth as much as $17 billion.

Verizon said its board had authorized management to explore the sale or spinoff of its Verizon Information Services directories unit to focus on its core wireless, broadband Internet and major corporate phone businesses.

With its traditional local phone business gradually shrinking, Verizon has pushed into new areas such as providing video and high-speed Internet access over fiber-optic lines. Shedding the directories business would allow it to focus on this and other faster-growing sectors, such as wireless.

The company did not disclose in a statement released late yesterday how much the directories business, which had revenue of about $3.5 billion last year, might be worth. A source familiar with the company's plans who was not authorized to speak about them in detail and so spoke on condition of anonymity said a deal could be worth as much as $17 billion.

New York-based Verizon, the dominant local phone company in the Washington area, said the Texas-based directories unit had 7,300 employees and controlled the local search portal.

Verizon is expected to close on its $8.5 billion purchase of Ashburn-based MCI Inc. by early next year.