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ISDN
Issue 5 January 1998
12-15555-230-024
■ User-to-User Information sends user information from one endpoint to
another using the D channel. Three forms are available: message
associated data, sent within Q.931 call control messages during call
establishment and call clearing; call-associated data, sent during call
setup on a B channel; and noncall-associated data, sent with no related
call-setup activity on the B channel. Applications for this feature include
DCS, Look-Ahead Interflow, and display of calling party name and
number.
DEFINITY ECS’s support of ISDN-PRI, ISDN-BRI, and available public network
services means that you can achieve full end-to-end ISDN connectivity and take
advantage of ISDN services and features. For example, two switches connected
by Primary Rate Interface can exchange calling party name and/or number infor-
mation. The information is displayed on the called party’s telephone. In addition,
the called party’s ID is also displayed at the calling party’s telephone. This lets
users identify the source of an incoming call before answering. Computer tele-
phone integration interfaces can also use the information provided by the net-
work to integrate your communications and data-processing systems.
The ISDN-BRI Trunk circuit pack allows DEFINITY to support the S/T interface as
defined by ISDN standards (ITU-T recommendation I.411). The circuit pack pro-
vides eight ports to the network and each port supports two B channels and one
D channel. ISDN-BRI Trunk provides the following advantages:
■ Provides an inexpensive way to connect to ISDN services provided by the
network provider.
■ Meets all ETSI protocol requirements and almost all country-specific
requirements.
■ Supports essential (not supplementary) ISDN services.
DEFINITY ECS also adds the following capabilities to the basic ISDN services,
depending on local availability of support.
■ ISDN flow control monitors message activity on the Primary Rate Interface
D channel.
■ Non-Facility-Associated Signaling allows a Primary Rate Interface D
channel to supply signaling for B channels (voice and data) located on
Primary Rate Interface interfaces other than the one where the D channel
is found. As a result, one D channel can support call control and signaling
for up to 20 Primary Rate Interfaces.
■ D Channel backup, when administered, improves reliability in the event of
a signaling link failure on a Non-Facility-Associated Signaling D channel
group. A primary D channel provides signaling for the Non-Facility-
Associated Signaling D channel group (two or more Primary Rate
Interface facilities). A second D channel, located on a separate Primary
Rate Interface facility of the same Non-Facility-Associated Signaling D
Channel group, is designated as a backup. If the primary D channel fails,
call-control signaling automatically transfers to the backup D channel.