Angela Lang/CNET

AT&T has won a $984 million, 15-year contract to help upgrade the US Department of Justice's technology systems. The deal will see AT&T move more than 120,000 DOJ employees in 2,100 offices to a new communications platform for mobile voice and data, cybersecurity and cloud services. While it doesn't cover 5G for now, the next-generation networking service could be added on later.

The DOJ and 43 attached organizations will also get access to FirstNet, a dedicated public safety network with better security, speed and priority.

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Stacy Schwartz, AT&T's vice president of public safety and FirstNet, said it will help support the Justice Department's "hard work of protecting the freedoms, rights and safety of all Americans."

The deal is part of the federal government's Enterprise Infrastructure Solutions technology procurement program.