TETRA (Terrestrial Trunked Radio) is a set of standards developed by the European Telecommunications Standardisation Institute (ETSI) that describes a common mobile radio communications infrastructure throughout Europe.
This infrastructure is targeted primarily at the mobile radio needs of public safety groups (such as police and fire departments), utility companies, and other enterprises that provide voice and data communications services.
All of these groups have been high-end users of private/professional mobile radio (PMR) or public access mobile radio (PAMR) technology. This is especially true in the areas of law enforcement and public safety, where fast and accurate field communications to and from a central office or dispatcher are often critical. TETRA is a standard solution for groups that use both PMR and PAMR.