isdn

IPA/ˌaɪ.es.diːˈen/
IPA/ˌaɪ.es.diːˈen/

isdn — noun

1. a set of rules for sending sound, images, and computer data at high speed throug

1.nounB2
Definition

a set of rules for sending sound, images, and computer data at high speed through the copper wires of a telephone network — used mainly in the 1990s and 2000s before faster internet connections became common.

Example

The publishing house used an ISDN line to send large image files to the printer.

ISDN + noun (ISDN line)

Xiu remembered how slow the internet felt before her office switched from ISDN to broadband.

Common collocations
  • ISDN line
  • ISDN connection
  • ISDN router
  • set up ISDN
  • switch from ISDN to broadband
  • ISDN network
  • ISDN service
Synonyms
  • broadband

    a broader, more modern term for any high-speed internet; ISDN was a specific early form of broadband

  • DSL

    a later digital technology that also uses phone wires but offers much higher speeds than ISDN

Antonyms
  • dial-up

    an older, slower technology that uses the same phone wires but cannot carry voice and data at the same time

Grammar Patterns

ISDN + noun (e.g. ISDN line, ISDN connection)

Usage Note

ISDN is typically uncountable (ISDN is a standard). When used attributively before another noun — ISDN line, ISDN connection — no article is needed. The technology has largely been replaced by DSL, cable, and fiber-optic broadband, so examples commonly appear in past-tense or historical contexts.

Common Mistakes

I need to buy an ISDN' (countable error).
I need an ISDN connection.
ISDN is an uncountable noun referring to a standard; you need a second noun (line, connection, service) for countable use.

2. the short form of the words 'Integrated Services Digital Network' — a digital te

2.nounB2
Definition

the short form of the words 'Integrated Services Digital Network' — a digital telephone network that can send sound, images, and computer information at the same time over standard phone wires.

Example

ISDN stands for Integrated Services Digital Network, a telecommunications standard from the 1980s.

stands for + full name

The job advertisement asked for experience with ISDN, short for Integrated Services Digital Network.

short for [full name]

Common collocations
  • stands for
  • short for
  • the acronym ISDN
  • the abbreviation ISDN
Synonyms
  • acronym

    a broader category; ISDN is one example of an acronym, pronounced as individual letters or as a word

  • initialism

    a term for abbreviations spoken letter by letter, though ISDN is often said as a word /ˈaɪzdən/

Grammar Patterns

ISDN stands for [full name]

Usage Note

This sense is relevant only when the speaker is explaining or expanding the acronym itself. In most everyday contexts (e.g., 'Do we have ISDN?') the TECHNOLOGY STANDARD sense applies. The full expansion is always capitalised: Integrated Services Digital Network.

Synonym discussion

Sense: noun/1

ISDN, broadband, DSL, and dial-up all refer to ways of connecting to a telephone network or the internet, but they differ by speed, technology, and era. ISDN (Integrated Services Digital Network) was a 1980s–1990s digital standard that sent voice and data over copper phone wires at up to 128 kbps — fast for its time but slow by modern standards. Broadband is a general term for any high-speed internet connection (typically above 256 kbps) and includes DSL, cable, and fiber services. DSL (Digital Subscriber Line) is a later technology that also uses phone wires but reaches much higher speeds (megabits per second) without blocking voice calls. Dial-up is the oldest and slowest method, using a modem to call an internet provider over an ordinary phone line, occupying the line completely. For example: 'Our office moved from dial-up to ISDN in 1996, then switched to DSL around 2003.'

ISDN ↗broadband ↗DSL ↗dial-up ↗

Common collocations

Nouns

Phrases

  • set up ISDN
  • switch from ISDN to broadband
  • rely on ISDN
  • use ISDN
  • support ISDN
  • provide ISDN service

Etymology

Englishacronym

ISDN is an acronym formed from the first letters of 'Integrated Services Digital Network'. The term was coined in the 1980s by the International Telecommunication Union (ITU) to name a new digital telephone network standard that would replace older analog systems. 'Integrated Services' refers to the ability to carry different types of communication (voice, video, data) over a single network, and 'Digital Network' describes the use of digital signals rather than analog ones.