APCO P25 Standard

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Project 25 (P25 or APCO-25) is a suite of North American digital radio communication standards for digital public safety radio communications. It was launched in 1988 as a step beyond the old-fashioned two-way voice contact between first responders and their dispatchers, with the dispatchers serving as the link to other agencies when necessary, generally over a telephone line.

It began when Congress directed the Federal Communications Commission (FCC) to collect recommendations from users and manufacturers. Based on the recommendations of the Association of Public-Safety Communications Officials-International (APCO), Project 25 then came into existence. In scope, this was unprecedented, but it wasn’t just happening in North America. Europe’s Terrestrial Trunked Radio (TETRA) protocol standards are a parallel effort, with much in common, but the two are not compatible.

P25 Concepts

Understanding P25 in a  proper context, it’s all about standards. On a technical level, there is one fundamental rule for P25. Compliant radios may communicate in analog mode with legacy radios and in either digital or analog mode with other P25 radios. Beyond that, P25 standards allow considerable flexibility.


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