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
Telematic, data transmission and teleconference services operations and quality of service : recommendations F.160 - F.353, F.600, F.601, F.710 - F.730 / International Telecommunication Union
Message handling and directory services operations and definition of service : recommendations F.400 - F.422, F.500 / International Telecommunication Union