Federal officials said Thursday that AT&T will build a major wireless broadband network for first responders. The contract is worth $6.5 billion dollars, and billions more are expected to be spent on building out and operating the network.

This is a big step for the network, called FirstNet, which grew out of concerns on 9/11 about the inability of first responders to communicate with each other in an emergency. But the project has been troubled.

Why it matters: AT&T gets 20 megahertz of wireless spectrum to deploy as part of the project. That's primarily meant to be used for first responders, but the company can use excess network capacity to serve its customers — a boon given demand for wireless data has been on the rise. States are allowed to opt-out of the network, however, and develop their own systems.