 After all of the above study, only the five words representing the letters C, M, N, U, and X were replaced.The ICAO sent a recording of the new "Radiotelephony Spelling Alphabet" to all member states in November 1955.The final version given in the table above was implemented by the ICAO on , and the ITU adopted it no later than 1959 when they mandated its usage via their official publication, "Radio Regulations".