General Charging and Accounting Principles for International Telecommunication Services Provided over the Integrated Services Digital Network (ISDN) - Charging and Accounting in International Telecommunication Services (Study Group 3) 7 pp
The ITU-T, considering that an Integrated Services Digital Network (ISDN) provides digital connections between user-network interfaces, enabling Administrations to offer integrated access to a wide range of international services in association with a multi-service signalling system.