This listing is comprised of the nationally recognized "National Interoperability Field Operations Guide (NIFOG)" frequencies for the United States, as well as the legacy frequencies that have been given new universal nomenclatures.
Many public safety agencies have some or all of these channels available to them. Their use and availability will depend on each agency. These channels may be used for small or wide area incidents and should be monitored during such multiagency incidents. As such, these channels will NOT be in the normal local database listings unless a different squelch tone is in use for the local area.
Many legacy law enforcement, fire and EMS freq's are known by different names throughout the country, but their use is fairly consistent. The channel names listed here, are listed by their new nationally recognized nomenclature, and are not officially part of the NIFOG. For example, a common law enforcement mutual aid frequency of 155.475 has been known as: National, NLEEF, NLER, LERN, LEEN, LEN, etc. It is now known as VLAW31. Even with the new naming, the older names may still persist when monitoring such channels.
Many channels are also setup for repeater operation. Each of those channels have a corresponding direct channel which is the same as the repeater output. Therefore if you hear a mention of 8TAC91D, it is the same output frequency of 8TAC91. Since the output frequency is the same, the channels with the "D" suffix will not be listed separately.
VTAC17 is the same as Marine Channel 25 and may only be used in areas at least 100 miles from a navigable waterway, and by ground stations only.
Please refer to the wiki article for notes regarding the use of CTCSS tones on Low Band, VHF, UHF, and 800 Public Safety Common frequencies.
Frequencies used commonly are also listed in the "public safety" categories. Although they are listed in the official NIFOG documentation, they are not nationwide interoperable frequencies.
As of April 2019, the current NIFOG revision is 1.6.1A. The database is broken down into its NIFOG format for easier readability.
(In the event of a discrepancy in nomenclature or usage, the current NIFOG found at the US Department of Homeland Security, Cybersecurity and Infrastructure Security Agency web page will take precedence).