Computer Networks: The Physical Layer

2.5 Narrowband ISDN

Highlights

2.5.1 ISDN Services

ISDN services offer data transmission services in addition to the normal voice services, so that information relevant to a call can be accessed at the same time as the call is answered, and it can be accessed on the same line.

2.5.2 ISDN System Architecture

The ISDN's digital bit pipe does not care what kind of digital information is being sent on it--all data is treated the same way. Since businesses and homes use their communications differently, two different standards for ISDN have been developed: one for the home (low bandwidth) and one for businesses (high bandwidth).

2.5.3 The ISDN Interface

The different services and data rates offered by ISDN are named for letters of the alphabet (A, B, C, D, E, H) in the standards.

2.5.4 Perspective on N-ISDN

The first ISDN services that were developed are now called Narrowband ISDN because they have a lesser data transmission rate than the newer Broadband ISDN (B-ISDN). ISDN will likely be implemented most often for fast Internet access, since other services such as video on demand will be better suited for B-ISDN.

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