Acronym for International Telecomunication Union.
Website: 
http://www.itu.int/
the ITU are the group that standardises telecommunications protocols and standards. They have three types of major documents Technical standards (ITU-T), Radio Communications (ITU-R) and Design (ITU-D).
See also ITU-T.
2 pages link to ITU:
lib/main.php:944: Notice: PageInfo: Cannot find action page