In the 1980s, the

telecommunications industry The telecommunications industry within the sector of information and communication technology comprises all telecommunication/ telephone companies and Internet service providers, and plays a crucial role in the evolution of mobile communications ...

expected that digital services would follow much the same pattern as voice services did on the

public switched telephone network The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists o ...

, and conceived an end-to-end circuit switched service, known as Broadband Integrated Services Digital Network (B-ISDN).

History

Before B-ISDN, the original

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. ...

attempted to substitute the analog telephone system with a digital system which was appropriate for both voice and non-voice traffic. Obtaining worldwide agreement on the

basic rate interface Basic Rate Interface (BRI, 2B+D, 2B1D) or Basic Rate Access is an Integrated Services Digital Network (ISDN) configuration intended primarily for use in subscriber lines similar to those that have long been used for Plain old telephone service, ...

standard was expected to lead to a large user demand for ISDN equipment, hence leading to mass production and inexpensive ISDN chips. However, the standardization process took years while

computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

technology moved rapidly. Once the ISDN standard was finally agreed upon and products were available, it was already obsolete. For home use the largest demand for new services was video and voice transfer, but the ISDN basic rate lacks the necessary

channel capacity Channel capacity, in electrical engineering, computer science, and information theory, is the theoretical maximum rate at which information can be reliably transmitted over a communication channel. Following the terms of the noisy-channel coding ...

. This led to introduction of B-ISDN, by adding the word

broadband In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...

. Although the term had a meaning in physics and engineering (similar to

wideband In communications, a system is wideband when the message bandwidth significantly exceeds the coherence bandwidth of the channel. Some communication links have such a high data rate that they are forced to use a wide bandwidth; other links ma ...

), the CCITT defined it as: "Qualifying a service or system requiring transmission channels capable of supporting rates greater than the primary rate" referring to the primary rate which ranged from about 1.5 to 2 Mbit/s. Services envisioned included video telephone and

video conferencing Videotelephony (also known as videoconferencing or video calling) is the use of audio signal, audio and video for simultaneous two-way communication. Today, videotelephony is widespread. There are many terms to refer to videotelephony. ''Vide ...

. Technical papers were published in early 1988. Standards were issued by the Comité Consultatif International Téléphonique et Télégraphique (CCITT, now known as ITU-T), and called "Recommendations". They included G.707 to G.709, and I.121 which defined the principal aspects of B-ISDN, with many others following through the 1990s. The designated technology for B-ISDN was

Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT) for digital trans ...

(ATM), which was intended to carry both

synchronous Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or ''in time''. Systems that operate with all parts in synchrony are said to be synchrono ...

voice and

asynchronous Asynchrony is any dynamic far from synchronization. If and as parts of an asynchronous system become more synchronized, those parts or even the whole system can be said to be in sync. Asynchrony or asynchronous may refer to: Electronics and com ...

data services on the same transport. The B-ISDN vision has been overtaken by other disruptive technologies used in the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

. The ATM technology survived as a low-level layer in most

digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

(DSL) technologies, and as a payload type in some wireless technologies such as

WiMAX Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options. The WiMA ...

. The term "broadband" became a marketing term for any digital

Internet access Internet access is a facility or service that provides connectivity for a computer, a computer network, or other network device to the Internet, and for individuals or organizations to access or use applications such as email and the World Wide ...

service.

History

See also

References

Further reading