The ITU or The International Telecommunication Union was originally founded as the International Telegraph Union. The ITU is based in Geneva, Switzerland; its membership includes 193 Member States and around 700 Sector Members and Associates.
It falls under the jurisdiction of the United Nations and deals with issues that concern communication technology and information. Coordination of the global shared use of the radio spectrum is facilitated by the ITU. The ITU also assigns satellite orbits internationally, assists in the development and coordination of worldwide technical standards and also works to improve telecommunication infrastructure in the developing world.
Other areas that the ITU is involved with are: aeronautical and maritime navigation, radio astronomy, latest-generation wireless technologies, satellite-based meteorology broadband Internet, convergence in fixed-mobile phone, Internet access, data, voice, TV broadcasting, and next-generation networks.

There are three main sectors of the ITUI, each managed by a different chairperson as well as different concerns of telecomm. The information below was taken from the article : http://en.wikipedia.org/wiki/International_Telecommunication_Union
The three sectors of the ITU are
Radiocommunication (ITU-R)
Managing the international radio-frequency spectrum and satellite orbit resources is at the heart of the work of the ITU Radiocommunication Sector (ITU-R).
Standardization (ITU-T)
ITU’s standards-making efforts are its best-known – and oldest – activity; known prior to 1992 as the International Telephone and Telegraph Consultative Committee or CCITT (from its French name “Comité consultatif international téléphonique et télégraphique”)
Development (ITU-D)
Established to help spread equitable, sustainable and affordable access to information and communication technologies (ICT).