ACRO.IT Acronym Directory

A set of CCITT/ITU standards for digital communication that operates over existing analog telephone lines. ISDN was first published as one of the 1984 ITU-T Red Book recommendations. ISDN uses mostly existing Public Switched Telephone Network (PSTN) switches and wiring, upgraded so that the basic call is a 64 kilobits per second, all-digital end-to-end channel.