MERLIN LEGEND Communications System Release 6.1
Feature Reference
555-661-110
Issue 1
August 1998
Features
Page 89Basic Rate Interface (BRI)
Description 3
BRI, like PRI, is a standard protocol for accessing Integrated Services Digital
Network (ISDN) services. By using BRI, the MERLIN LEGEND Communications
System can connect its users to the speed and accuracy of ISDN services.
National ISDN-1 (NI-1) BRI service is available for MERLIN LEGEND
Communications System Release 4.0 and later systems only.
BRI lines offer the capability of voice, high-speed data, local area network (LAN)
interconnection, and video transmission. BRI lines (along with PRI and T1
Switched 56) also allow you to take advantage of the 2B Data feature for
videoconferencing systems with ISDN-BRI interfaces. The 2B Data feature allows
one application (such as a desktop video system or a high-speed digital
communications device) to use two B-channels for data transfer rates up to 128
kbps. For more information, see “Digital Data Calls” on page 200
.
The following benefits are provided by NI-1 BRI service:
■ Speed. Data calls to outside destinations can be established on the same
B-channels used for voice calls if the service allows; modems and
dedicated, conditioned lines/trunks are not needed. By supporting
high-speed digital data transmission, BRI provides the capability for
videoconferencing and Group IV (G4) fax by using existing wiring. Each
B-channel supports up to 64 kbps throughput.
■ Improved Toll Restriction. The ways that toll restriction can be bypassed
are limited on BRI lines/trunks. Specifically, three types of toll fraud are
eliminated with BRI service:
— Because dialing is in the form of out-of-band messages that must be
generated by the system, a person cannot use a touch-tone generating
device, such as a pocket dialer, to send dialed digits directly through the
system to the line/trunk.
— Without BRI service, toll restriction can be deceived by dialing digits on a
loop-start line before the far-end switch applies dial tone. These initial
digits may indicate a local call to the system’s toll-restriction checking
while the subsequent digits, those actually recognized by the far-end
switch, may produce a toll call. This is not possible with BRI service
because every dialed digit is screened by the system’s toll-restriction
check.
— A BRI line’s far-end disconnect signal provides a reliable indication
when a call ends, and a new call cannot be initiated until the line has
been released from the prior call on both ends. This prevents a person,
waiting off hook for the restoration of dial tone after a previous call, from
placing a second call before toll restriction is reapplied.
■ Reliable Indication of Far-End Disconnect. This prevents an incoming
call from being blocked because a line/trunk has not been released when a
call is ended.
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