X.25 was originally defined by the International Telegraph and Telephone Consultative Committee (CCITT, now ITU-T) in a series of drafts and finalized in a publication known as The Orange Book in 1976.
X.25 נוצר במקור על ידי ה International Telegraph and Telephone Consultative Committee - CCITT וכיום ITU-T כסדרת טיוטות עד לפרסום הסופי במסגרת The Orange Book בשנת 1976.