Instruction manual

DEFINITY® Business Communications System and GuestWorks® Issue 6
Overview
555-231-208
Issue 1
April 2000
Networking Solutions
9-10ISDN
9
ISDN
The system provides a complete set of ISDN features. Demonstrating its role as a
leader in making ISDN a universal reality, Lucent Technologies makes it possible
for anyone connected to the system to benefit from ISDN capabilities and
features.
ISDN eliminates the need for multiple, separate access arrangements for voice,
data, facsimile, and video services and networks. Using the same pair of wires
that now carry simple telephone calls, ISDN can deliver voice, data, and video
services in digital format.
ISDN is a global access standard established by the Consultative Committee for
International Telephone and Telegraph designed to help you move and manage
information with unprecedented ease and productivity — anywhere in the world.
ISDN uses a layered protocol that conforms to layers one, two, and three (physi-
cal, link, and network layers) of the seven-layer Open Systems Interconnect Ref-
erence Model of the International Standards Organization.
The system supports the two major interfaces specified in the ISDN standards —
PRI and BRI.
■ PRI is used for connecting premises equipment to the network, and acts as
a powerful interface between intelligent equipment such as systems and
computers.
■ BRI is used for connecting telephones, computers, personal computers,
and other desktop devices to other computer equipment.
The system also supports an optional adjunct that converts ISDN-PRI lines to a
trunk-side ISDN-BRI. A single PRI is converted to up to eight BRIs plus a propri-
etary 2 Mbps expansion interface. See your Lucent Technologies representative
for more information about this adjunct.
Both PRI and BRI are based on the same common building blocks — the use of a
common interface to a transmission path that is divided into channels. Both PRI
and BRI use two types of channels for communication:
■ Bearer channels are the communications links in ISDN. They provide 64
kbps digital communications service for voice, data, video, and other
information transmission.
■ Delta channels, sometimes known as data channels, are the signaling links
in ISDN. They carry call-control and call-related information, such as caller
ID, between ISDN endpoints.