Lucent Technologies MERLIN LEGEND Release 6.1 System Manager's Manual page 70

MERLIN LEGEND Communications System Release 6.1
System Manager's Guide 555-661-118
2 About the System
Incoming Trunks
— Digital Signal 1 Facility Programmed for Either T1 or Primary Rate
NOTE:
Facility is a general term that designates a communications path between
a telephone system and the telephone company central office. Specifically,
we refer to digital facilities (sometimes called pipes ). Technically, a trunk
connects a switch to a switch, for example, the MERLIN LEGEND
Communications System to the central office. Technically, a line is a loop-
start facility or a communications path that does not connect switches, for
example, an intercom line or a Centrex line. However, in actual usage, the
terms line and trunk are often applied interchangeably. In this guide, we
use lines/trunks and line/trunk to refer to facilities in general. We also use
specific terms such as personal line , ground-start trunk , DID trunk , and so
on. When you talk to personnel at your local telephone company central
Interface Operation (Incoming and Outgoing Calls). One Digital Signal
1 (DS1) facility provides the equivalent of 24 lines, called channels . In
Release 4.0 and later systems, the DS1 facility can be programmed to
operate in one of three ways:

T1 Voice Operation. A "line" can be programmed through the
system, without the services of a telephone company installer, to
emulate a ground-start, loop-start, tie, or DID trunk. This type of T1
operation also gives you access to special services, such as inbound
800 or WATS service for incoming, toll-free service for voice calls.
Only this type of T1 operation is available in releases prior to Release
4.0.
NOTES:
1. While you can quickly and easily change the type of line
that a channel imitates, you must coordinate the change
with the T1 provider so that both ends of the connection are
set up for the same type of line/trunk.
2. In Release 6.0 and later systems (Hybrid/PBX mode only),
tandem PRI lines can be used for networking. In this case,
you order a T1 facility and program it for PRI operation. For
more information, see the Network Reference .
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T1 Data Operation. Available in Release 4.0 and later systems, T1
data operation allows high-speed data communications over the
public switched network; this is called T1 Switched 56 service . It also
provides data tie "lines" to connect one MERLIN LEGEND
Communications System to another or to a DEFINITY system. A T1
data-operation "line" is a channel .

Primary Rate Interface (PRI) Operation. The 24 "lines" include 23
B-channels. Each B-channel can dynamically provide voice and data
services; one D-channel carries signaling information for the
B-channels.
Issue 1
August 1998
Page 2-15