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Appendix C. A brief ISDN glossary 225
• Cold insertion/removal - Denotes the installation or removal of a peripheral
device when the computer system is powered off and/or disconnected from
the wall sockets.
• D channel - The second type of channel in ISDN BRI line. It carries 16 kbit/s
and is mainly limited to signaling functions to control the B channels.
• D-channel switching protocol - Describes the telephone company's particular
implementation of ISDN. The switching protocol is one of the key elements
that determines whether a given ISDN adapter can be used in a given country.
D channel switching protocols in use include:
— DSS1: Digital Subscriber System No. 1, commonly used in Europe where it
is also called E-DSS1 or Euro ISDN
— NI-1: National ISDN 1, used in the United States of America and Canada
— 5ESS: AT&T switching protocol, used in the United States of America and
Canada
— G3 PBX Custom: AT&T switching protocol, used in the United States of
America and Canada
— DMS-100 Custom: Nortel protocol, used in the United States of America
and Canada
— NTT INS Net 64: NTT Docomo, used in Japan
— TPH 1962: obsolete D-channel switching protocol used in Australia;
replaced by DSS1
— 1TR6: obsolete D-channel switching protocol used in Germany; replaced
by DSS1.
• DCE - Data communication equipment
• dpi - Dots per inch: a measurement unit for image resolution.
• DTE - Data terminal equipment
• E carrier system - E1 (or E-1) is a European digital transmission format
devised by the ITU-TS and given its name by the Conference of European
Postal and Telecommunication Administrations (CEPT). It is the European
equivalent of the North American T carrier system format. E2 through E5 are
carrier signals in increasing multiples of the E1 format..
The E1 signal format carries data at a rate of 2,048 Mbit/s and thus can carry
32 channels of 64 kbit/s each. E1 carries at a somewhat higher data rate than
T1 (1.544 Mbit/s) because, unlike T1, it does not use bit-robbing, so that all
eight bits per channel are used for signal encoding. E1 and T1 can be
interconnected for international use.
The E1 signal format carries data at a rate of 2,048 Mbit/s and thus can carry
32 channels of 64 kbit/s each. E1 carries at a somewhat higher data rate than
T1 (1.544 Mbit/s) because, unlike T1, it does not use bit-robbing, so that all
eight bits per channel are used for signal encoding. E1 and T1 can be
interconnected for international use.
• ETSI - European Telecommunications Standards Institute.
• Euro ISDN - The D-channel switching protocol adopted throughout Europe.
In 1989, 18 telephone companies from different European states signed a
ISDNmst.fm Page 225 Wednesday, January 15, 2003 9:22 AM