DMR TIER I
DMR Tier I products are for licence-free use in the European 446 MHz band. In the US, the 446 MHz range is primary US Government with the amateur radio service a heavy secondary user. Some DMR radios that make it across the ocean have caused interference issues with licensed amateur operations. Tier 1 equipment is FDMA.
This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power.
DMR TIER II
DMR Tier II covers hand portables, mobiles and base stations operating in the VHF and UHF allocations for PMR.
The ETSI DMR Tier-2 standard is targeted to those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. ETSI DMR Tier-2 calls for two slot TDMA in 12.5 kHz channels.
DMR TIER III
DMR Tier III covers trunking operation in frequency bands 66-960MHz. The Tier III standard specifies two-slot TDMA in 12.5kHz channels. Tier III supports voice and short messaging handling similar to MPT-1327 with built-in 128 character status messaging and short messaging with up to 288 bits of data in a variety of formats. It also supports packet data service in a variety of formats, including support for IPv4 and IPv6.