Meaning of ISDN in English
Integrated Services Digital Network; A telecommunications technology that enables data to be passed along two regular phone wires at 128,000 bits per second, or 56,000-64,000 bits per second for a single phone line. Compare this with the typical modems of today (around 33,600 bits per second).
Internet PR English glossary. Английский словарь Интерет пиара и продвижения. 2012