The electromagnetic spectrum defined as radio waves is chopped up into bands by regulatory agencies, including the World Radio Organization and the Federal Communications Commission. Each band is assigned to certain service.
Public safety is just one of the many services that is assigned specific sets of frequencies.
The following list shows the current U.S. frequency assignments, with primary users shown first in the list, followed by other services that may use the frequencies if primary users haven't requested assignments. The public safety bands are highlighted. All figures are in megaHertz. Police , fire and EMS agencies are frequently assigned channels in the local government and special emergency bands. Some of the assignments are designated for the general category of public safety .