CCITT - A French acronym that stands for the International Consultative Committee on Telephony and Telegraphy. It is a United Nations sponsored standards body within the ITU, the International Telecommunications Union. It is responsible for specifying, among other things, the OSI protocol model and the X.25, X.3, X.28, and X.29 standards. It is also responsible for internationally agreed upon standards for modems such as V.34.