Integrated services digital network (ISDN) : overall network aspects and functions, ISDN user-network interfaces: recommendations I.310 - I.470 / International Telecommunication Union
Integrated services digital network (ISDN) : internetwork interfaces and maintenance principles: recommendations I.500 - I.605 / International Telecommunication Union
Maintenance of international telegraph, phototelegraph and leased circuits : maintenance of the international public telephone network: maintenance of maritime satellite and data transmission systems: recommendations M.800 - M.1375 / International Telecommunication Union
Maintenance of international sound-programme and television transmission circuits : series N recommendations / International Telecommunication Union