International Telecommunication Union
The International Telecommunication Union (ITU) is an international organization established to standardise and regulate international radio and telecommunications. Its main tasks include standardization, allocation of the radio spectrum, and organizing interconnection arrangements between different countries to allow international phone calls. (In which regard it performs for telecommunications a similar function to what the UPU performs for post.) It is one of the specialized agencies of the United Nations.
See also the ITU-T and ITU-R and the website http://www.itu.int/ ITU are also the initials of "International Typographical Union", a now defunct(?) labor union that was affiliated with the Congress of Industrial Organizations.