Bay Networks 6300, Supplement Manual

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A-7
Chapter 1 Introduction to the Remote Annex 6300
Remote Annex 6300 Supplement to the Remote Annex Administrator’s Guide for UNIX
Book A
• Identification of the switch type used by the telephone company.
This information is required to set up the user’s ISDN
equipment properly.
• Obtaining a Service Profile Identifier (SPID) from the telephone
company for each device connected to the ISDN BRI or PRI.
The SPID lets the telephone company switch know which ISDN
services a particular device can access. The user needs to know
each device’s SPID to set up that device to work on the ISDN
line.
ISDN Standards Compliance
ISDN is based on a set of digital transmission protocols defined by the
International Telecommunications Union (ITU).
Although ISDN standards are accepted worldwide, universal adoption is
not yet a reality. There are two causes for the lack of universal standards-
based service.
First, many United States telephone companies must modernize their
switches to perform call signaling through Signaling System 7 (SS7). SS7
(an international standard) specifies that ISDN D channel carry all call
set up, tear down, and connection management signaling exclusively. In
the United States, some telephone companies with older switches must
use a portion of BRI B channels to carry part of this signaling. As a result,
these companies offer BRI B channel transmission rates at 56Kbps, not
at the full ISDN bandwidth of 64Kbps.
Second, many digital telephone switches were installed while ISDN
standards were evolving. At that time, switch vendors (e.g., AT&T and
Nortel) offered switches with custom ISDN capabilities. As a result, there
are differences in the ISDN service features offered by local telephone
companies.