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Trunk Management
DEFINITY Enterprise Communications Server Release 8.2
Overview
555-233-002
Issue 1
April 2000
ISDN Trunks
Gives you access to a variety of public and private network services and facilities. The
ISDN standard consists of layers 1, 2, and 3 of the Open System Interconnect (OSI)
model. DEFINITY ECS can be connected to an ISDN using standard frame formats:
Basic Rate Interface (BRI) and the Primary Rate Interface (PRI).
An ISDN provides end-to-end digital connectivity and uses a high-speed interface which
provides service-independent access to switched services. Through internationally
accepted standard interfaces, an ISDN provides circuit or packet-switched connectivity
within a network and can link to other ISDN supported interfaces to provide national and
international digital connectivity.
Integrated Services Digital Network—(Basic Rate
Interface (ISDN-BRI)
Enables connection of the system to equipment or endpoints that support an Integrated
Services Digital Network (ISDN) by using a standard format called the Basic Rate
Interface (BRI). This feature is a 192-Kbps interface that carries two 64-Kbps B-channels
and one 16-Kbps D-channel.
ISDN is a global access standard that uses a layered protocol. It 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 a digital format.
The ISDN-BRI Trunk circuit pack allows DEFINITY ECS to support the T interface and the
S/T interface as defined by ISDN standards (ITU-T recommendation I.411). The circuit
pack provides eight ports to the network and supports two B channels and one D
channel. The ISDN-BRI Trunk provides the following advantages:
■ Provides an inexpensive way to connect to ISDN services provided by the network
provider
■ Meets almost all ETSI Country protocol requirements
■ Supports essential (not supplementary) ISDN services
BRI trunks support public-network access outside the U.S. on point-to-midpoint
connections, with the restriction that DEFINITY ECS must not be configured in a passive
bus arrangement with other BRI endpoints. ISDN-BRI trunks can be used as inter-PBX tie
lines using the QSIG peer protocol.
233002_1.book Page 78 Monday, February 21, 2000 8:28 AM