Fiber Optic Wiki

ISDN is very popular in Germany

December 13, 2011

In Germany, ISDN is very popular with an installed base of 25 million channels (29% of all subscriber lines in Germany as of 2003 and 20% of all ISDN channels worldwide). Due to the success of ISDN, the number of installed analog lines is decreasing. Deutsche Telekom (DTAG) offers both BRI and PRI. Competing phone companies often offer ISDN only and no analog lines.

Demand for spectrum in the US

December 12, 2011

In the United States, more of the broadcast spectrum was needed for wireless broadband Internet access, and in March 2009, Massachusetts Senator John Kerry introduced a bill requiring a study of efficient use of the spectrum.

Integrated Services Digital Network

December 12, 2011

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

ISDN should not be mistaken for its use

December 12, 2011

ISDN should not be mistaken for its use with a specific protocol, such as Q.931 whereby ISDN is employed as the network, data-link and physical layers in the context of the OSI model. In a broad sense ISDN can be considered a suite of digital services existing on layers 1, 2, and 3 of the OSI model. ISDN is designed to provide access to voice and data services simultaneously.

ISDN elements and integrated services

December 12, 2011

Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line. Multiple devices can be attached to the line, and used as needed.

Basic Rate Interface

December 12, 2011

The entry level interface to ISDN is the Basic(s) Rate Interface (BRI), a 128 kbit/s service delivered over a pair of standard telephone copper wires. The 144 kbit/s payload rate is broken down into two 64 kbit/s bearer channels ('B' channels) and one 16 kbit/s signaling channel ('D' channel or delta channel). This is sometimes referred to as 2B+D.

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