Two plenipotentiary conferences were held in 1932 at Madrid—one covering telephone and telegraph and the other radiotelegraph communication. The two existing conventions were amalgamated into a single International Telecommunication Convention (the word telecommunication signifying "any transmission, emission or reception of signs, signals, writing, images and sounds, or intelligence of any nature by wire, radio, optical, or other electromagnetic systems"). The countries accepting the new convention, which came into force on 1 January 1934, formed the International Telecommunication Union.
The International Telecommunication Convention of 1932 has been revised six times. The Plenipotentiary Conference of the ITU, meeting in Atlantic City in 1947, radically changed the organization to keep up with developments in telecommunication: for example, a new permanent organ, the International Frequency Registration Board, was created to cope with the overcrowding of certain transmission frequencies; and an agreement was drawn up under which the ITU was recognized by the UN as the specialized agency for telecommunication. The convention was further modified in certain respects by plenipotentiary conferences in 1952, 1959, 1965, 1973, and 1982.
In 1989, the Plenipotentiary Conference held in Nice created a High-Level Committee to propose wide-ranging recommendations about the role of ITU in a world totally transformed by the convergence of telecommunications and computer technology and the globalization and privatization of telecommunications providers. An historic Additional Plenipotentiary Conference was convened in Geneva in December 1992 to adopt far-reaching structural changes to the union and a thoroughly revised constitution and convention. The new constitution officially entered into force on 1 July 1994. However, the structural changes were considered so important to maintaining the organization's relevance in the rapidly changing technological world that the new structure was implemented as of 1 March 1993. The Constitution has been amended at subsequent plenipotentiary conferences.