03 What is the CCITT ITA-2 Code?

Baudot code – Wikipedia

To facilitate character entry, Donald Murray around 1901 developed a keyboard similar to that of a typewriter, which punched the associated string of five bits into a punched tape by pressing a single key.

Murray retained Baudot’s level switching, but rearranged the order of characters in the code so that frequently used letters, such as “E” and “T” were given code positions that required shorter and less frequent movement of the mechanics in the equipment to send and receive. This reduced wear and tear and the need for maintenance. Murray also added a carriage return character to subdivide telegrams.

Another important change was that spaces and letter/digit switching were separated and became separate characters. To be able to drive sheet recorders (devices that write line by line on a sheet instead of endlessly on a strip), control characters for carriage return and line feed were added. Added to this was a code for triggering an automatic name generator on the remote device to make sure who you were connected to (Who there?) even if the remote station was unmanned, as well as the ability to trigger a bell to get the attention of the operator.

Dieser so veränderte Code wurde 1926 von der CCITT als Internationales Telegrafenalphabet Nr. 2 (kurz CCITT-2 oder ITA2) vorgeschlagen und nach einer Anpassung 1929 standardisiert. 

Eine weitere Anpassung erfolgte bereits 1931.

Die Veröffentlichung erfolgte im Journal télégraphique im August 1931: “L’unification des alphabets à cinq impulsions”.


Die aktuellen Empfehlungen der ITU zum ITA-2 finden sich unter S.1 : International Telegraph Alphabet No. 2 (itu.int)