Project 25



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Project 25


When an emergency strikes, whether it is a multi-car accident or a hurricane, first responders need to coordinate an effective response. And at the heart of an effective response is the radio communications between officers in the same agencies and across multiple agencies. Around the world, public safety agencies have worked with industry leaders to develop and enhance a standard called Project 25 to enable interoperable communications.


Project 25 (P25) is a suite of standards for mission critical digital two-way radio communication equipment published by the Telecommunications Industry Association (TIA). It is an evolving standard uniquely developed by both equipment manufacturers and public safety users to meet the needs of the public safety community around the world. The Project 25 standard enables interoperability between multiple manufacturer's P25 products designed to the P25 standard.




The Project 25 standard has a twenty year history within the public safety community. It was established in October 1989 when APCO (Association of Public Safety Communications Officials), NASTD (National Association of State Telecommunications Directors), NCS (National Communications System), NTIA (National Telecommunications and Information Administration), and NSA (National Security Agency) agreed to the creation of the APCO-NASTD-FED Project 25. Since the beginning, the standard has been unique in that it has had the involvement of public safety agencies along side industry leaders.



Project 25 is widely adopted by public safety agencies across North America including local, county, tribal, state, and federal agencies. It also has the support of the US Department of Homeland Security (DHS). The DHS Office of Emergency Communications in coordination with the Office of Interoperability and Compatibility developed the annual SAFECOM Recommended Guidance for Federal Grant Programs.


Around the world, government agencies from Australia to Russia to South America have also adopted Project 25 systems for their mission critical communications.


In addition, the P25 standard is adopted by many industries such as utilities, airports, transit, petroleum, and chemical companies that rely on mission critical communications and interoperability with governmental public safety agencies in an emergency.



The Project 25 suite of standards continue to expand as new technological enhancements and innovations become available. There are eight interfaces that make up the suite of standards with the most recent additions being the Phase 2 TDMA Common Air Interface (CAI) and the Inter-RF Subsystem Interface (ISSI).



The Project 25 CAI standard specifies the type and content of signals transmitted by compliant radios. One radio using the P25 CAI is able to communicate with other P25 CAI radios, regardless of manufacturer.

The CAI is the most widely deployed Project 25 interface in the suite of standards. It is available as Phase 1 FDMA protocol and will soon be available for Phase 2 TDMA protocol. The new Project 25 Phase 2 TDMA standardized interface will meet the FCC regulatory requirements for 6.25 kHz spectrum efficiency in the VHF, UHF and 700 MHz band plans. The TDMA standard adds a Phase 2 TDMA voice service to the existing Phase 1 FDMA trunked voice and packet data services available today.