Errestrial trunked radio (TETRA) is a professional mobile radio and two-way transceiver specification designed for use by government agencies, emergency services (police forces, fire departments, ambulances) for public safety networks, rail transportation staff for train radios, transport services, and the military. https://hallbook.com.br/blogs/809652/Terrestrial-Trunked-Radio-Market-Growth-Driven-by-Advanced-Connectivity-Trends