The Effects of Non-P25 Digital Systems on Interoperability
Wednesday, July 17, 2013 | Comments

The Association of Public-Safety Communications Officials (APCO) Project 25 (P25) standard began 20 years ago to set standards for digital public-safety radio communications. Previously APCO developed standards for public-safety analog trunked radio systems called Project 16. The shortcoming of Project 16 was it was too broad and allowed for manufacturers to develop proprietary public-safety trunked radio systems. This resulted in disparate radio systems within a city or county that could not communicate with each other, creating many interoperability issues.

The P25 vision was to set a digital radio standard, conventional and trunked, for all manufacturers to build to so that a public-safety agency would not be locked in to one vendor’s proprietary radio system but instead have multiple vendors from which to purchase digital radio systems, mobiles and handheld equipment. Numerous P25 conventional and trunked radio systems are in service with multiple manufacturers radios operating on the systems. Department of Homeland Security (DHS) grants specified digital radios to be P25 compliant. But in the past few years, manufacturers have started making and marketing proprietary digital, non-P25 compliant radio systems. These proprietary digital radios don’t work on P25 radio systems.

While the non-P25 digital radios work well, help resolve frequency congestion and typically are sold for less cost than P25 radios, the result is setting interoperability efforts back several years. In several cases the proprietary digital radios have caused interference to existing analog radio users more than 100 miles away. This is mainly limited to the VHF 150 MHz band, but some interference has occurred in the UHF band. Many state or neighboring agencies to those using the non-P25-compliant radios have been forced to purchase these non-P25 radios for officer safety and to try to foster interoperability among agencies, costing public-safety agencies additional funds that were often not budgeted.

Some manufacturers of the non-P25 compliant digital radios say the radios are not designed for the public-safety market, but vendors are selling the radios to law enforcement, fire departments and EMS services. While the DHS Office of Emergency Communications (OEC) has and continues to work diligently to help public safety prepare for disaster response and foster interoperability between jurisdictions and disciplines, the various non-P25 digital radios are moving public safety away from interoperability.

What can be done to reverse this trend? First, manufacturers could lower their P25-compliant radio equipment to equal or lower cost than the noncompliant proprietary digital radios. Second, those who purchase P25 non-compliant radios must incorporate the nationwide, state and local mutual-aid and interoperability frequencies into their radios using the American National Standards Institute (ANSI) standard channel names. This would include, but is not limited to, the VHF VCALL10 and VTAC 11-14, VLAW31, VFIRE 21-26, VMED28, UCALL 40 and UTAC 41-43 and any other local or state interoperability or mutual-aid channels designated in their state communications interoperability plan (SCIP) or tactical interoperability communications plan (TICP).

Third, manufacturers could discourage mobile-communications dealers from selling non-P25 compliant radios to law enforcement, fire, EMS, emergency management agencies and other first response groups. Fourth, ensure that the digital radios purchased with DHS or other federal grants are P25 compliant. Fifth, continue to build relationships with other agencies, disciplines and jurisdictions to be prepared, and participate in communications planning, training and exercises.

The DHS Office of Emergency Communications (OEC) offers many interoperable technical assistant initiatives to help with disaster preparedness. Contact your statewide interoperability coordinator (SWIC) or visit



John Johnson works for the Lafayette Group as a communications unit leader/technician (COML/COMT) instructor and works on public-safety communications projects. He retired from the Tennessee Emergency Management Agency (TEMA) after 31 years of state government service. Johnson serves as the Association of Public-Safety Communications Officials (APCO) International local frequency advisor for the state of Tennessee, chairman of the Region 39, Tennessee, 700 MHz National Public Safety Planning Advisory Committee (NPSPAC) committee, and is the immediate past chair of the 800 MHz regional planning committee and the statewide interoperability committee.

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On 3/26/19, andrew foltz said:
With Project 25 (P25) radios on UHF and VHF, can those noncompliant systems interfere on a broader scale if their bandwidth skirts a nearby signal that is compliant?


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