From the National Association of Regional Planning Committees:
The availability of a considerable number of multi-discipline 700 MHz interoperability channels, allong with exisiting 800 MHz mutual aid channels, can provide a bridge of interoperability in communities currently using disparate trunked radio systems operating in the 800MHz public safety band. In many areas, conventional channel implementation use is the only radio resource common denominator between personnel of multiple agencies using disparate trunked radio systems in a community.
Every public safety radio on the BRICS system contains thirty interoperability channels in the 700MHz band to provide additional ways to communicate off our system and with other responders nationwide.
These channels operate in digital mode, similar to our trunked system, and will usually have excellent audio quality at an incident scene. They are located in zones W and X. With the exception of the calling channels, they are direct (simplex) or radio to radio. You can use them without having coverage on a trunked system. They will provide clear, digital and short range communication at an emergency scene that is “off the network”.
The names of these channels are standardized by the National Public Safety Telecommunications Council.
Download the NPSTC Standard Channel Nomenclature Report (PDF) on all public safety interoperability channels.
The name of the channel indicates the intended use. There are two calling channels in 700MHz: 7 CALL 50 and 7 CALL 70. We intend to put repeaters on these frequencies in 2010.
The other channel types are:
TAC: Public Safety Tactical
GTAC: General Government and Non-Governmental Organizations
MOB: Mobile Repeaters
LAW: Law Enforcement
FIRE: Fire Departments
MED: Emergency Medical Services