Terrestrial Trunked Radio (TETRA)

Terrestrial Trunked Radio (formerly known as Trans-European Trunked Radio) is a professional mobile radio and two-way transceiver (colloquially known as a walkie talkie) specification.

TETRA was specifically designed for use by government agencies, emergency services, (police forces, fire departments, ambulance) for public safety networks, rail transport staff for train radios, transport services and the military. It operates as a two-way transceiver and is popularly used by the emergency services as well as on transport such as rail and on marine vessels. The use of low frequencies allows for far greater transmission distances but lower data transfer rates. TETRA provides for authentication of terminals towards infrastructure and vice versa. For protection against eavesdropping; air interface encryption and end-to-end encryption is available.