ISDN - Inter-Network

Japanese: ISDN - あいえすでぃーえぬ
ISDN - Inter-Network

Abbreviation for integrated service digital network. It is also translated as integrated digital communications network, integrated service digital network, etc. A network that enables large-capacity transmission through digital technology, it is a system that integrates telecommunications networks that were previously constructed separately, such as telephone, data communications, and facsimile, using optical fiber cables and communications satellites to provide them to customers. It is an international common standard proposed in 1980 by the Consultative Committee for International Telegraph and Telephone (CCITT), the predecessor of the International Telecommunication Union (ITU).

Nippon Telegraph and Telephone Company (NTT) also started this service in 1988 (Showa 63) as part of the Advanced Information and Telecommunications System (INS). INS Net 64 (transmission speed 64 kilobits per second x 2) was launched in 1988, and INS Net 1500 (1.5 megabits per second) service began the following year in 1989 (Heisei 1). With a maximum transmission speed of 1.5 megabits per second, there is also an international ISDN service connecting to the United States and the United Kingdom. This is also called N-ISDN (narrowband ISDN). Furthermore, W-ISDN (broadband ISDN), a broadband system with a speed of 155 megabits per second, has been developed, but has not yet been put to practical use.

N-ISDN was popular mainly among small and medium-sized businesses, but in the 21st century, the number of people canceling their contracts has been increasing due to the popularity of the Internet. The NTT Group, which switched the core part of its fixed-line telephone network to the IP system in 2010, is moving to broadband services using optical fiber, and plans to stop its N-ISDN services around 2025 when its switching equipment reaches the end of its lifespan.

[Michinori Iwata]

[Reference] | Advanced Information and Telecommunications Systems | International Telecommunication Union | Information Superhighway Concept | Nippon Telegraph and Telephone Corporation

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

サービス総合デジタル網integrated service digital networkの略称。統合デジタル通信網、総合サービスデジタル網などの訳もある。デジタル技術によって大容量伝送を可能にしたネットワークのことで、電話、データ通信、ファクシミリなど、従来はばらばらに建設されていた電気通信網を、光ファイバーケーブルや通信衛星を用いて統合し、顧客に提供するシステム。1980年に国際電気通信連合(ITU)の前身の国際電信電話諮問委員会(CCITT)が提唱した国際的な共通規格である。

 日本電信電話会社(NTT)でも、高度情報通信システム(INS)の一環として1988年(昭和63)よりサービスを開始している。1988年に開始されたのはINSネット64(伝送速度毎秒64キロビット×2)で、翌1989年(平成1)からはINSネット1500(毎秒1.5メガビット)のサービスが始まった。伝送速度が最大毎秒1.5メガビットで、アメリカ、イギリスと接続した国際ISDNサービスも行われている。これらは、N-ISDN(狭帯域ISDN)ともよぶ。さらに、毎秒155メガビットの広帯域のW-ISDN(広帯域ISDN)が開発されてはいるが、まだ実用化されていない。

 N-ISDNは中小企業中心に普及したものの、21世紀になるとインターネットにおされて解約者が増えてきている。2010年(平成22)に固定電話網の基幹部分をIP方式に切りかえたNTTグループは、光ファイバーによる広帯域型のサービスに移行し、N-ISDNによるサービスは交換機が寿命を迎える2025年ごろには停止する予定。

[岩田倫典]

[参照項目] | 高度情報通信システム | 国際電気通信連合 | 情報スーパーハイウェー構想 | 日本電信電話(株)

出典 小学館 日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について 情報 | 凡例

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