Professional Mobile Radio (also known as Private Mobile Radio (PMR) in the UK and Land Mobile Radio (LMR) in North America) are field radio communications systems which use portable, mobile, base station, and dispatch console radios and are sometimes based on such standards as MPT-1327, TETRA and APCO 25 which are designed for dedicated use by specific organizations. Typical examples are the radio systems used by police forces and fire brigades. Key features of professional mobile radio systems can include:

- Point to multi-point communications (as opposed to cell phones which are point to point communications)
- Push-to-talk, release to listen — a single button press opens communication on a radio frequency channel
- Large coverage areas
- Closed user groups
- Use of VHF or UHF frequency bands

When Private or Professional Mobile Radio (PMR) first started the systems simply consisted of a single base station with a number of mobiles that could communicate with this single base station. These systems are still in widespread use today with taxi firms and many others using them for communication. Now facilities such as DTMF and CTCSS provide additional calling selection. Because the antenna may be mounted on a high tower, coverage may extend up to distances of 50 kilometres, although ranges somewhat less than this are more usual, especially when antennas are not as high.

Licenses are allocated for operation on a particular channel or channels. The user can then have use of these channels to contact the mobile stations in their fleet. The base station may be run by the user themselves or it may be run by an operating company who will hire out channels to individual users. In this way a single base station with a number of different channels can be run by one operator for a number of different users and this makes efficient use of the base station equipment. The base station site can also be located at a position that will give optimum radio coverage, and private lines can be provided to connect the users control office to the transmitter site. As there is no incremental cost for the transmissions that are made, individual calls are not charged, but instead there is a rental for overall use of the system. For those users with their own licences they naturally have to pay for the licence and the cost of purchase and maintenance of that equipment.
TETRA is a modern standard for digital Private Mobile Radio (PMR) and Public Access Mobile Radio (PAMR).

Work started on the development of the TETRA standards in 1990 and has relied on the support of the European Commission and the ETSI members. Experience gained in the development of the GSM cellular radio standard, as well as experience from the development and use of trunked radio systems has also been used to fashion the TETRA standard. In addition to this the process has gained from the co-operation of manufacturers, users, operators and industry experts. With this combined expertise the first standards were ready in 1995 to enable manufacturers to design their equipment to interoperate successfully.

TETRA allocates the channels to users on demand in both voice and data modes. Additionally national and multi-national networks are available and national and international roaming can be supported. For civil systems in Europe the frequency bands 410-430 MHz, 870-876 MHz / 915-921 MHz, 450-470 MHz, 385-390 MHz / 395-399.9 MHz, have been allocated for TETRA. Then for the emergency services in Europe the frequency bands 380-383 MHz and 390-393 MHz have been allocated. In addition to this, the whole or appropriate parts of the bands between 383-385 MHz and 393-395 MHz can be utilized.

Low speed packet data as well as circuit data modes are available, along with some form of encryption. The systems makes use of the available frequency allocations using Time Division Multiple Access (TDMA) technology with four user channels on one radio carrier with 25 kHz spacing between carriers.

TETRA is available in almost every country in the world with the notable exception of North America where it is kept out by Motorola who refuse to licence key patents (on reasonable terms) for this market and also do not offer the technology themselves.