This page has been archived and is no longer actively maintained by the FCC, but is presented here for its potential historical value.

In this article, we will use the terms "interoperability", "mutual aid", and "mutual assistance" interchangeably. Traditionally, interoperability meant operating a radio network with pre-defined procedures and parameters, such as frequency, power, modulation scheme, network management, etc., that were shared among all of the intended operators in the network. Perhaps the most difficult part of coordinating all of these operating parameters though is the management piece, or "governance" in the SAFECOM Interoperability Continuum. Recall also that interoperability is defined in Section 90.7 of the Commission's rules as "[a]n essential communications link within public safety and public service wireless communications systems which permits units from two or more different entities to interact with one another and to exchange information according to a prescribed method in order to achieve predictable results."

In order to encourage interoperability within the public safety community, the FCC has been proactive in predefining a set of non-Federal, or national, interoperability channels in designated public safety spectrum bands. These channels were designed to provide the public safety community with a set of channels with predetermined operational parameters that could serve as a basis for initial on-the-scene coordination and resolution of local interoperability issues. This article addresses the Federal Interoperability Channels and the non-Federal Nationwide Mutual Aid Channels and reiterates the importance of using these channels for resolving initial interoperability - getting the people to people issues resolved!

Beginning in 1996, the Commission began a series of proposed rule makings and eventual orders that gave guidance and direction for the establishment of a system for public safety coordination and use of designated PS channels across the nation.2This included allocations in the high frequency (HF), very high frequency (VHF), and ultra-high frequency (UHF) bands. Initial allocations were based on narrowband applications for voice-based services only. The proceedings eventually included assignments in the reallocated 700 MHz and 800 MHz bands and included wideband services. Based on narrowband applications, the process eventually led to further narrowbanding from analog 25 kHz voice channels to digital channels of 12.5 kHz and subsequently to 6.25 kHz channels. Project 25 was a follow-on effort on the part of the Association of Public Safety Communications Officials (APCO) to establish various protocols for the use of these redesignated digital narrowband channels.3

In the process, the Commission also established a series of national mutual aid channels. The national mutual aid channels were designed to provide multiple agencies with a common set of operating frequencies and parameters for specific uses in an incident location; for example, common frequencies for fire, police, or emergency medical services. The use of these frequencies is guided by the regulations of the National Telecommunications and Information Administration (NTIA) for frequencies designated for Federal users and the Federal Communications Commission for frequencies designated for non-Federal use.4These rules are intended to provide minimal constraints on the use of the mutual aid frequencies but do provide specific guidelines for the coordination and use of the frequencies. Federal users may use the non-Federal channels only for interoperability with (and at the invitation of) a non-federal entity; non-Federal users may use the Federal channels only for interoperability with (and at the invitation of) a Federal entity.

The Commission has designated interoperability channels in the following frequency bands:

  • Below 512 MHz:
    • 150-174 MHz: one calling channel and four tactical channels (0.25 megahertz total)
    • 156-162 MHz Band: two channel pairs for interoperability in thirty-three Economic Areas (EA), where these channels are allocated for public safety (.0375 megahertz total)
    • 220-222 MHz: ten channels for mutual aid. (.04 megahertz total)
    • 450-512 MHz: one calling channel and three tactical channel pairs (0.2 megahertz total)
  • 763-775/793-805 MHz Band:
    • Narrowband Interoperability Channels: sixty-four paired narrowband channels designated for nationwide interoperable voice and data communications (0.8 megahertz total).
      • Section 90.547 requires that mobile and portable transmitters operating on narrowband channels must be capable of operating on all of the designated nationwide narrowband interoperability channels.
    • Narrowband State Channels: a single geographic license issued to each state (2.4 megahertz).
    • Broadband: 10 megahertz allocated for a nationwide interoperable public safety broadband network to be provided via a public/private partnership.
  • 806-809/851-854 MHz Band: five channels for nationwide interoperable voice communications (0.125 megahertz total). See 47 C.F.R. § 90.617(a)(1).
  • 4.9 GHz Band: eighteen channels designated "to foster interoperability by providing a regulatory framework in which traditional public safety entities can pursue strategic partnerships with both traditional public safety entities, such as the Federal Government, and non-traditional public safety entities, such as utilities and commercial entities, in support of their missions regarding homeland security and protection of life and property." (50 megahertz total)

In order to assist Federal and non-Federal agencies and potential users of the mutual aid channels, the Department of Homeland Security has published the National Interoperability Field Operations Guide (NIFOG).5 It contains an organized listing of the national mutual aid channels as well as additional information to assist users in the field. The general use of a frequency is provided along with the NPSTC Channel Identification, the frequency of operation and any other parameter specifications. 6 The NIFOG is available by contacting DHS's Office of Emergency Communications at OEC@HQ.DHS.GOV.

Several sections of the existing rules provide additional guidance and rules for interoperability.

  • Section 2.103(a) permits Federal use of non-Federal frequencies in bands above 25 MHz (except the 700 MHz public safety bands) if the Commission finds that such use is "necessary for coordination of Federal and non-Federal activities."
  • Section 2.103(b) permits Federal use of 700 MHz narrowband and 4.9 GHz channels with non-Federal entities if the Commission finds such use necessary; where: (i) "the stations are used for interoperability or part of a Federal/non-Federal shared or joint-use system;" (ii) the Federal entity obtains the approval of the non-Federal licensee; (iii) the Federal operation comports with the Commission's rules and conforms with any conditions agreed upon by the Commission and NTIA; and (iv) "Interoperability, shared or joint-use systems are the subject of a mutual agreement between the Federal and non-Federal entities."
  • Section 1.203(c) permits Federal use of the 700 MHz broadband spectrum with non-Federal entities, where:
    • "The Federal entity obtains the prior approval of the Public Safety Broadband Licensee (and such approval granted by the Public Safety Broadband Licensee is consistent with the terms and conditions of the Network Sharing Agreement under Section 90.1406);" and
    • "Federal operation is in accordance with the Commission's Rules governing operation of this band and conforms to any conditions agreed upon by the Commission and NTIA."
  • Section 90.203(i) requires equipment certified after February 16, 1988 and marketed for public safety operation in the 800 MHz band to be programmed on the mutual aid channels.
  • Section 90.203(j)(1) provides that applications for certification received after January 1, 2005, for mobile and portable transmitters designed to transmit in the 150-174 MHz or 450-470 MHz bands, will be granted only if the equipment is capable of operating on the designated nationwide public safety interoperable calling channels.
  • Section 90.203(i) requires equipment in the 800 MHz band to have the capability to be programmed for operation on the mutual aid channels.
  • Sections 90.547(a) and 90.548 require mobile and portable narrowband radios to be capable of operating on the interoperability channels using the P25 standard to ensure that all public safety entities using 700 MHz narrowband radios will be able to communicate with each other.
  • Section 337 of the Communications Act provides public safety entities with a means of obtaining a Commission rule waiver to permit public safety entities to use frequencies not allocated for public safety use.
  • The Deficit Reduction Act of 2005 directed NTIA, in consultation with DHS, to establish and implement a $1 billion grant program to assist public safety agencies in the acquisition of, deployment of, or training for the use of interoperable communications systems that utilize, or enable interoperability with communications systems that can utilize, reallocated public safety spectrum for radio communications. The Digital Television Transition and Public Safety Act of 2005 authorized NTIA, in consultation with DHS, to make payments not to exceed $1 billion in the aggregate through fiscal year 2010 to carry out the Public Safety Interoperable Communications (PSIC) program. On September 30, 2007, the PSIC Grant Program awarded $968,385,000 to fund interoperable communications projects from the 56 States and Territories. Public safety organizations interested in PSIC funding were able to seek funding through their State Administrative Agency. The deadline for submission of each State and Territory's Investment Justification was December 3, 2007.
  • The 9/11 Commission Act of 2007:
    • Established a grant program for first responders based on specific risk-based evaluation criteria as administered by DHS.
    • Established the "Improved Communications for Emergency Response Grant Program" to provide grants to states and regions to carry out initiatives to improve interoperable emergency communications, including initiatives to achieve solutions to statewide, regional, national, and, where appropriate, international interoperability.
    • Required the Commission, in consultation with the Department of State, the Office of Emergency Communications of the DHS and the Office of Management and Budget to submit a report to Congress on the status of cross border interoperability issues between the U.S. and Mexico and the U.S. and Canada on November 2, 2007. The report was timely submitted.

It should be noted that these national mutual aid channels are pre-designated so all agencies and responders may prepare in advance for operations that may be out of their normal region of concern and with other agencies that are not in their normal sphere of operations. While these mutual aid channels may be preprogrammed in radios, the rules that govern mutual operation must be considered prior to any actual use.


These mutual aid channels are integral to the much larger topic of public safety frequency assignments. Coincident with these channel designations is the assistance to the public safety community that is authorized for the amateur radio community.

1 Much of the work presented in this topic is attributable to Mr. Jeff Cohen, Senior Legal Counsel in the Public Safety and Homeland Security Bureau, Mr. Zenji Nakazawa from the Policy Division of the Bureau, Mr. Thomas Eng, from the Policy Division, and Mr. Tracy Simmons from the Licensing Branch of Policy Division. In addition, we wish to thank Mr. Ross Merlin, from the Office of the Chief Information Officer, U.S. Department of Homeland Security, and the author of the DHS NIFOG, for his assistance. We are very grateful for their contributions.

2 See the list of references and proceedings under FCC WT Docket 96-86; "The Development of Operational, Technical, and Spectrum Requirements for Meeting Federal, State and Local Public Safety Agency Communication Requirements Through the Year 2010" at - enter "96-1492" in the box to the right of "DA/FCC Number" or "96-86" in the box marked "Docket Number". Initially the frequency coordination was done via the National Coordinating Committee (NCC) but was subsequently referred to each state under their State Interoperability Executive Committees (SIECs).

3 "Project 25 is a multi-phase, multi-year project to establish a standards profile for the operations and functionality of new digital narrowband private land mobile radio (LMR) systems needed to satisfy the service, feature, and capability requirements of the public safety communications community for procuring and operating interoperable LMR equipment." See the APCO P25 web site at

4 See section 4.3.16 for Federal frequency use under the rules of the NTIA. See Part 90 for Non-Federal frequency use under the rules of the FCC.

5 See

6 The channel identifications were determined by the National Public Safety Telecommunications Council (NPSTC) as part of the FCC rulemaking process. The Report of the Committee can be viewed at$file/Calsiec021907CNTGReport.pdf. See also An alternative version of the mutual aid channel listing is also available on the NPSTC web page at