Aeronautical mobile (OR) service

Aeronautical mobile (OR) service (short: AMS;  | also: aeronautical mobile radiocommunication service') is – according to Article 1.34 of the International Telecommunication Union´s (ITU) Radio Regulations (RR) – defined as «An aeronautical mobile service intended for communications, including those relating to flight coordination, primarily outside national or international civil air routes.»

Variations of this radiocommunication service in line to the ITU Radio Regulations article 1 are as follows :
Mobile service (article 1.24)

(R)° = abbreviation to route flights (route)
(OR)°° = abbreviation to flights others than on routes (off-route)

The allocation of radio frequencies is provided according to Article 5 of the ITU Radio Regulations (edition 2012).

In order to improve harmonisation in spectrum utilisation, the majority of service-allocations stipulated in this document were incorporated in national Tables of Frequency Allocations and Utilisations which is within the responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared.

However, military usage, in bands where there is civil usage, will be in accordance with the ITU Radio Regulations. In NATO countries military utilizations will be in accordance with the NATO Joint Civil/Military Frequency Agreement (NJFA).

US Navy Grumman C-2 UHF/VHF-Aircraft station used for Aeronautical mobile (OR) service

Airbus A319 in the Antarctic region

US Air Force transport aircraft on the Antarctic region

...
Wikipedia