In critical operations, communication services need to be available everywhere as it is impossible to predict where incidents, emergencies and disruption of operations may occur.

Extensive geographical network radio coverage is fundamental even in sparsely populated areas such as rural, mountain or desert regions where there is usually no or insufficient service from public cellular networks.

TETRA can provide rich and efficient off-network communication capabilities that allow field users to communicate everywhere (even outside network coverage) and in any occurrence (when the network is unavailable, overloaded, or to communicate independently from the network for local operations) through direct connection between devices (DMO – Direct Mode Operation).

Off-network direct communications can be further optimised in terms of coverage range through the use of devices acting as DMO repeaters or DMO gateways, the latter providing a local extension of a network base station to users operating in DMO (e.g. to provide immediate and prompt in-tunnel or in-door service).

Only dedicated communication networks can provide such a required level of service coverage and TETRA is natively conceived and constantly enhanced to provide extensive and cost effective coverage. TETRA can operate in low frequency bands thus minimising the required number of network sites and the high level of competition typical of the TETRA market catalyses continuous product improvement. Today TETRA radio terminals and base stations offer extremely optimised receivers with sensitivity levels well beyond the minimum required by the standard, thereby dramatically further improving TETRA coverage capabilities and cost effectiveness.


There are always circumstances both planned and unplanned when it is essential for mission critical users to operate outside the coverage of their network. It is a fundamental requirement to ensure that communications can be maintained between operational groups of users regardless of the scenarios they find themselves in.

Operation outside network coverage might be needed for a variety of reasons: to compensate for poor network signal strength areas, when service from a local base station site is lost, or there is a prior knowledge of operating in an area where there is no or poor network coverage. TETRA provides a range of off-network services to enable users to retain key services such as group calls, point to point calls, emergency calls and pre-emption, text messages and to maintain security and encryption used on network. TETRA’s off-network services are comprehensive and provide:

  • Back-to Back operation – communication directly between two or more devices
  • Repeater Operation – range extension using a standard TETRA device acting as a relay between other devices
  • Gateway operation – range extension back to the TETRA network, connecting devices working off-network to the TETRA network to maintain wide area coverage.
  • Long range communications – back-to back operation can extend to more than 3 km for handheld devices and much further for in-vehicle devices.

Off network services are provided in all standard TETRA devices and can be activated by the user simply selecting the required mode of operation.


The world’s critical users have a wide variety of requirements and use cases. Devices need to be available for many different types of use and be robust enough to withstand use in extreme environments while still delivering return on investment through length of service. Products are designed from first principles to be critical and secure, negating the need for constant security patches. Devices operate in a real time manner, performing their communications tasks within strict performance criteria and have predictable and repeatable responses to all critical actions (e.g. emergency button press), regardless of how the device is being used. The TETRA ecosystem covers a wide variety of use cases and devices are available in many form factors to suit user requirements. These include devices designed for front line public safety usage, for use in a range of vehicles: motorcycles, cars, vans, aircraft, boats, within control centre environments and for covert installations.

Devices are designed and built for durability, with a field deployment expectation of between five and seven years and supported life of much longer. Devices are designed with components that have long term support ensuring that products can be manufactured, maintained and supported throughout their life. All devices are supported by a wide variety of specialist accessories to fit the exacting needs of critical users’ demands.

All TETRA devices are subject to TCCA’s stringent and independently managed interoperability testing process, ensuring that a wide variety of cost effective compatible solutions from multiple vendors are available.

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