TETRA stands for TErrestrial Trunked RAdio, and is used for PMR (Professional Mobile Radio) as well as for PAMR (Private Access Mobile Radio) applications. As a trunked system, it is designed to replace MPT1327. TETRA applies digital speech transmission with TDMA (burst transmission), supports extremely fast call set-up times, and may also use powerful encryption (separate algorithms for private and public safety applications). TETRA users communicate from terminal to terminal (or between terminal and a dispatcher), rather than from/into the Public Switched Telephone Network (PSTN), although this is also possible. TETRA users include public safety organisations, which need to communicate via group calls as well as individual calls, and user groups like transport or service fleets (e.g. energy companies, taxis, and courier services).
