(Both agreement and application must be submitted)

Updated September 2012

Narrow Banding of Fire Mutual Aid Channels, New Frequency Naming Convention, Tone Squelch Requirements and the Missouri Statewide Interoperability Network (MOSWIN)

In order to facilitate the timely transfer to the federally mandated narrow banding of radio frequencies, the state of Missouri’s Department of Public Safety agencies (including the Division of Fire Safety) transferred all frequencies in use to narrow band emission on March 1, 2012.

The federal mandate is that all frequencies be operated solely on narrow banding emissions by Jan. 1, 2013.

Therefore, the division frequencies shared with Missouri’s fire service, Fire Mutual Aid and the five command frequencies are now to be operated in narrow band emissions.

The division has rewritten the frequency sharing agreement to address the use of frequencies licensed to the division and utilized for mutual aid responses.  In the past, the division operated three wide band and three narrow band frequencies. Now that all frequencies will be narrow band, the wide band frequencies will no longer negatively impact the use of the new narrowband frequencies.

The division has also instituted the federal naming conventions for these frequencies, which are listed below:

  • The frequency previously called Fire Mutual Aid will now be designated as VFIRE21.
  • The frequency previously called Command 1 will now be designated as VFIRE22.
  • The frequency previously called Command 2 will now be designated as VFIRE23.
  • The frequency previously called Command 3 will now be designated as VFIRE24.
  • The frequency previously called Command 4 will now be designated as VFIRE25.
  • The frequency previously called Command 5 will now be designated as VFIRE26.

Another important change will be to the tone squelch system associated with these frequencies. Following a recommendation contained within the National Interoperability Field Operations Guide (NIFOG), the division’s new frequency sharing agreement will mandate that all frequencies shall utilize continuous tone coded squelch (CTCSS) of 156.7 Hz added to the transmit audio function while no tone squelch shall be used on the receive audio function in order to limit radio interference while allowing all users to hear any other user on a non-tone squelched frequency or a frequency utilizing a different continuous tone coded squelch.

Additionally, the state is now well under way with the buildout and testing of Missouri’s new interoperable radio system known as Missouri Statewide Interoperable Network or MOSWIN. Details on the progress of this radio system and Missouri’s interoperable communications initiative are available at

Questions concerning changes to the division’s frequency sharing agreement may be addressed to Asst. State Fire Marshal Greg Carrell at (573) 751-2930.