Opinions and resolutions recommendations on the organization and working procedures of CCITT (series A) / International Telecommunication Union
Terms and definitions abbreviations and acronyms : recommendations on means of expression (series B): general telecommunications statistics (series C) / International Telecommunication Union
General tariff principles : charging and accounting in international telecommunication services: Series D recommendations / International Telecommunication Union
Telephone network and ISDN : operation, numbering, routing and mobile service: recommendations E.100 - E.333 / International Telecommunication Union