ISDN

[Sonia]

Stands for Integrated Services Digital Network. ISDN is a telecommunications technology that enables the transmission of digital data over standard phone lines. It can be used for voice calls as well as data transfers.
The first ISDN standard was defined in 1988 by the CCITT organziation, which is now the ITU-T (International Telegraph and Telephone Consultative Committee). However, it wasnt until the 1990s that the service became widely used. Since the introduction of ISDN, several variants have been standardized, including the following:
ISDN was a common high-end Internet service in the 1990s and early 2000s and was offered by many ISPs as faster alternative to dial-up Internet access. Many businesses and organizations used ISDN service for both Internet access and network connections between locations. In the mid-2000s, DSL and cable serviced began to replace ISDN connections because of their faster speed and lower cost. Today, ISDN is still used in some network connections, but it is rarely used for Internet access.
Netgear ISDN Router

[Jessica]

Integrated Services [Digital Network]
ISDN is a communications standard for sending voice, video, and data over digital telephone lines or telephone wires. It supports [data transfer] rates of 64 [Kbps] and can support two lines at once (calles B channels), which allow you to use both lines to transfer data; this gives you data rates of 128 Kbps.

[Kai]

It [still] does [nothing].

[Zipporah Schumaker]

abbreviation for Integrated Services Digital Network: a system for sending voice, video, and information over phone wires very quickly