Also known as: ITU, International Telecommunication Union
The International Telecommunication Union (ITU) is the United Nations specialised agency for information and communication technologies.1 It coordinates the global radio spectrum and publishes the international Radio Regulations — the treaty that every national regulator writes its own rules within.2
Overview
Founded in 1865 as the International Telegraph Union, the ITU is the oldest of the UN’s specialised agencies and today has more than 190 member states plus hundreds of private-sector and academic members. Its work is carried out through three sectors. ITU-R (Radiocommunication) manages the radio-frequency spectrum and satellite orbits and publishes the Radio Regulations; its recommendations underpin systems such as AIS and DSC. ITU-T (Standardization) produces telecommunication standards, including the widely used G-series voice codecs like G.711 and G.729. ITU-D (Development) works on bridging the connectivity gap in developing countries.
The central document for radio is the Table of Frequency Allocations, which slices the spectrum from 8.3 kHz upward into bands and assigns each to one or more radio services (fixed, mobile, broadcasting, maritime, aeronautical, amateur, radiolocation, space, and more). To manage regional differences the ITU divides the globe into three regions — Region 1 (Europe, Africa, the Middle East and northern Asia), Region 2 (the Americas) and Region 3 (most of Asia-Pacific) — each of which can carry slightly different allocations. This treaty framework is periodically revised at the World Radiocommunication Conference (WRC), where member states negotiate changes. National regulators such as the FCC, Ofcom and the US NTIA then translate these international allocations into domestic band plans and licences. The ITU also administers the international callsign prefix blocks and the Master International Frequency Register, and coordinates satellite filings to avoid orbital and frequency interference.
Relevance to SDR
The ITU’s allocations are the reason specific signals live in specific bands worldwide, which is what makes an SDR usable at all: when you see marine traffic near 156–162 MHz, aircraft ADS-B at 1090 MHz, or the amateur bands where hobbyist digital modes live, you are looking directly at the Table of Frequency Allocations. Understanding the region you are in explains why a band that carries one service in North America may carry a different one in Europe — a common source of confusion when following online tuning guides written for another region. The three-region split also explains why some land-mobile trunked-radio systems sit at different frequencies on different continents even when they run the same protocol.
Because the ITU-R sector authors the recommendations that describe several signals GopherTrunk and other decoders handle (AIS message formats, DSC, and the modulation of some maritime and aeronautical systems), the ITU indirectly shapes the bitstreams a decoder must parse. GopherTrunk itself does not implement any ITU allocation logic — it is a receiver and decoder — but every capture you feed it sits somewhere in the ITU’s global plan, and the Radio Regulations are the ultimate authority on what a given slice of spectrum is supposed to contain. For legal monitoring, remember that the ITU sets the international framework but your own national regulator sets what you may lawfully receive.
Sources
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International Telecommunication Union — Wikipedia, for the agency’s history, sector structure, and role. ↩
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International Telecommunication Union — the ITU’s official site, for the Radio Regulations, the Table of Frequency Allocations, and global spectrum coordination. ↩