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The following excerpts are from Mutual Aid and Common Frequencies Manual, Third Edition, Montana Department of Administration, Public Safety Radio Communications Program 2005.

Montana Mutual Aid and Common Frequencies

Mutual aid and common frequencies have come to be recognized as the most valuable public safety radio resource because they are the means by which responders from different agencies and different public safety services can communicate and interoperate. Rarely does an incident of any magnitude occur in which a single agency is the lone and sole service provider. Whether they are the standby EMS and fire suppression resources during a barricaded suspect call or the traffic control and evacuation resources during an urban interface fire, public safety agencies need to interoperate in today’s world of incident response.

No degree of interoperability is possible without common communications. In Montana, fourteen mutual aid and six common frequencies provide the basis for interagency radio communications.

Mutual aid refers to frequencies designated for interagency communications that are licensed statewide. Authorization for their use is given through agreement with the State of Montana.

The term common refers to frequencies designated for interagency communications, but not licensed statewide as mutual aid. They must be licensed by the using agency or used under agreement with a license holder for communications with that entity. Some are only available by agreement for communications with the license holder (e.g. State Lands and U.S. Forest Service common channels). For purposes of this manual, the term “common” will be used for frequencies recognized across the state.

Color Names

The term “mutual aid” means different things to different people, even when restricted to radio. When used to name a frequency or particular channel, it often leads to confusion over just which mutual aid frequency is being referred to. In public safety radio where clarity and simplicity of communications are essential, long and contrived names for basic tools are burdensome. For this reason, the color names on the following page are offered for use in reference to mutual aid and common frequencies.

Each is also given a descriptive title to clarify its use. Color names were chosen because the names are short, commonly recognized, and have been linked with associative memory.

The following is a list of Mutual Aid and Common Frequencies in Montana:


Frequency Color Usage 153.905 GOLD State Common Mutual Aid 155.475 BLUE National Law Enforcement Emergency 155.790 SILVER State Law Enforcement Mutual Aide 153.800 BLACK State Tactical Team Coordination 154.070 RED State Fire Mutual Aid 154.280 MAROON State Fire Comand & Control 154.265 CORAL State Fireground #1 154.295 SCARLET State Fireground #2 153.830 RUBY State Fire Repeater 159.345 GARNET State Fire Repeater Control 155.280 WHITE State Local Hospital to Ambulance 155.340 TAN State Regional Hospital to Ambulance 155.325 GRAY EMS Central Region Dispatch & Paging 155.385 PINK EMS East/West Region Dispatch & Paging


Frequency Color Usage 155.820 BROWN State DES Direction & Control 155.160 VIOLET National Search & Rescue 155.220 PURPLE State Search & Rescue 151.220 YELLOW State Foresty -- DNRC 171.475 GREEN US Forest Service Common