The prime vendor selection came under a Homeland Security-managed, indefinite-delivery/indefinite-quantity Tactical Communications Equipment and Services contract.
The value of the contract, which has a two-year period of performance and three one-year options, is $3 billion.
"We believe that open standards and the ability to select tactical communications solutions based on performance will provide first responders access to reliable solutions, which are essential to performing their mission," said Thomas Harvey, senior vice president, AT&T Government Solutions.
"Based on our experience with tactical communications deployments at the local, state and federal level, we believe TacCom provides (Homeland Security) a strong platform to modernize their infrastructure."
The TacCom contract enables the Homeland Security Department and its component agencies to purchase, at low cost, a wide range of tactical communications products, infrastructure and services to support public safety communications.
ATT said that under the contract, it is eligible to compete for task orders in all five service categories.