Verizon Communications Inc. and AT&T Inc. on Wednesday won a 10-year, nearly $1 billion deal to provide the Homeland Security Department with a secure telecommunications network, an agency spokesman said.

As prime contractor, Verizon will receive up to $679 million to consolidate multiple wide area networks shared by the department’s 22 agencies into one secure Internet Protocol-based network. Verizon will manage the network for DHS employees at more than 5,000 sites worldwide.

The New York-based company will also provide mobile communications services to help the department better respond to emergencies, said DHS spokesman Larry Orluskie.

The department will rely on AT&T, which will receive a maximum of $292 million, as a backup services provider.

The DHS deal is the largest award made under the so-called Networx Universal contract, considered the federal government’s largest telecom initiative.

Verizon, along with AT&T Inc. and Qwest Communications International Inc., were selected last March by the General Services Administration to be on that Networx contract. While not guaranteed business, the three contract winners won the right to compete with each other for the business of dozens of federal agencies needing to enhance the quality and security of voice, video and data technologies.

Last September, AT&T nabbed a 10-year, $270 million contract from the Treasury Department _ now the second largest deal awarded under Networx Universal.