DMR Tier I is a range of DMR frequencies that have been allocated by the European Telecommunications Standards Institute (ETSI) for licence-free use in the European Union.

DMR Tier I defines 16 channels for DMR use between 446 MHz and 446.2 MHz, allowing anyone to purchase Tier I compatible radio equipment and use it straight away. Tier I also defines that the maximum power emitted by each radio is less than 500 mW; for comparison, Motorola Solutions most popular radio has a maximum power of 5 W (10 times higher).

The 16 DMR Tier I frequencies are not allocated so equipment using these frequencies has the potential to be interfered with by other users in the area. This interference may cause you communication issues in business-critical situations, which is why you should be mindful of the risks before purchasing DMR Tier I equipment.

DMR Tier II is radio equipment that can operate anywhere within the DMR frequency range, but usually operates within the 136 - 174 MHz band for VHF and 403 - 527 MHz band for UHF. DMR Tier II equipment must be licenced from the frequency licencing body in your country which will avoid issues with interference and low power that happen with DMR Tier I equipment.

DMR Tier II equipment can utilise repeater stations to increase the range of the system, allowing you to build up a radio infrastructure to meet your geographical requirements.

DMR Tier III radio equipment works on the same frequency range as Tier II equipment but adds in many features to give the system more functions to better fit your situation. Tier III equipment operates in “Trunked mode”, which means radios are automatically allocated to frequencies rather than having a fixed frequency.

Trunking allows you to licence fewer frequencies while maintaining the same number of calls, lowering licence costs. Automatic allocation of frequencies removes the likelihood of two groups trying to communicate using the same channel and interfering with each other, which is especially important in large systems.

DMR Tier III adds data services which grant the radios SMS capability, location-based (GPS) services, telemetry data, and over-the-air programming, as well as remote control of radios such as the ability to stop radios transmitting which have been accidentally left on.