ITU (International Telecommunication Union)

The International Telecommunication Union is the UN specialised agency for global telecommunications, and for spaceflight its radiocommunication arm (ITU-R) is sovereign infrastructure: it maintains the Radio Regulations — the binding international treaty governing spectrum use — allocates frequency bands to services, and runs the coordination system through which every satellite network claims interference-free use of its frequencies and, for geostationary systems, an orbital slot. The mechanics run through national administrations: an operator's government files its proposed network with the ITU, the filing is examined and published, affected administrations coordinate, and successful networks are entered in the Master International Frequency Register with priority over latecomers. The system's currency is date-of-filing precedence, tempered by bringing-into-use deadlines so paper satellites cannot hoard spectrum indefinitely — pressure that has intensified as non-geostationary mega-constellations file for thousands of satellites and multiple gigahertz of Ka-band and beyond. World Radiocommunication Conferences, held every three to four years, amend the rules as technology moves.