TETRA (Terrestrial Trunked Radio) is a set of standards developed by the European Telecommunications Standardization Institute (ETSI) that defines a mobile radio communications infrastructure. Initially designed for European use, TETRA has become globally adopted by public safety organizations, utility companies, and other professional users who require reliable voice and data communications.

TETRA was created for high-end users of Private Mobile Radio (PMR) and Public Access Mobile Radio (PAMR), such as law enforcement, fire departments, and utility services. These groups rely on fast, efficient communication for critical operations. TETRA serves as a modern digital solution, replacing outdated analog systems with improved voice quality, faster data transmission, and enhanced spectrum efficiency through digital trunking.

TETRA combines features from various technologies, including mobile radio, digital cellular, paging, and wireless data, offering capabilities like encrypted communication, high data transfer rates, and advanced system management.

While TETRA was initially developed for Europe, its adoption has expanded worldwide. To reflect its global use, ETSI renamed it from Trans-European Trunked Radio to Terrestrial Trunked Radio. Countries such as Denmark, China, and the United States have embraced TETRA, alongside other standards like APCO 25 for public safety.

In 2012, the FCC (Federal Communications Commission) amended its Part 90 rules to allow TETRA systems in the 450-470 MHz and 809-824/854-869 MHz frequency bands. This opened the U.S. market for TETRA, making it legal for amateur radio use in certain bands.

The availability of second-hand TETRA equipment has introduced exciting opportunities for the amateur radio community. Operators can now legally experiment with TETRA systems, leveraging their professional-grade capabilities for personal and experimental use in approved frequency bands.

TETRA systems rely on two key identifiers to manage network access:

• MCC (Mobile Country Code): A three-digit code identifying the country of operation. For example:
  • MCC for the United States: 310
  • MCC for the United Kingdom: 234

• MNC (Mobile Network Code): A two- or three-digit code identifying the network operator within a country.

The combination of MCC and MNC uniquely identifies the network, ensuring proper routing and user management, especially in international or cross-border contexts.

Amateur radio operators exploring TETRA gain access to features like:

• High-quality voice communication
• Fast data transmission compared to analog systems
• Digital trunking for efficient spectrum usage

These features make TETRA an appealing choice for amateurs interested in experimenting with cutting-edge communications systems.

As of 2012, FCC regulations permit amateur operators to use TETRA equipment in specific frequency bands in the United States. Similar allowances exist in other countries, enabling hobbyists to experiment with TETRA while adhering to local regulations.

TETRA's inclusion in amateur radio provides access to advanced communication technology originally designed for mission-critical operations.

TETRA repeaters can be listed on RepeaterBook, where their details may include:

• MCC (Mobile Country Code)
• MNC (Mobile Network Code)

• RepeaterBook TETRA Repeaters