AT&T activated new 700MHz spectrum on more than 2,500 cell sites across the country since March as it presses ahead with deployment of FirstNet, a nationwide network for emergency responders.

The operator said it is in the process of adding the airwaves, also known as Band 14 spectrum, to more than 10,000 additional sites. AT&T noted the work is being conducted across all 50 states plus Puerto Rico and added the spectrum is already on-air for testing in more than 40 states.

Chris Sambar, SVP for AT&T FirstNet, said in a statement the operator’s build “is based off direct feedback from the states and public safety community. So, each current or new site to get Band 14 helps to meet public safety’s specific network needs.”

As well as adding the spectrum to existing sites, AT&T said its FirstNet plans call for the construction of more than 1,000 new sites to help close rural coverage gaps. However, it did not provide a timetable for construction of the sites.

AT&T launched ruthless pre-emption in December 2017 to give first responders priority on its commercial network while construction of the dedicated network is underway. It followed up in March with the debut of its FirstNet network core, which separates public safety from commercial traffic and supports FirstNet-specific functions.

Band 14-compatible devices are already available to first responders, as are Satellite Cell on Light Trucks (SatCOLTs), mobile cell sites which can boost connectivity as needed during large events and emergencies.

The operator said more than 1,500 public safety agencies have already signed up for FirstNet service, accounting for more than 110,000 connections on the network.