Lucent Technologies MERLIN LEGEND 6 System Manager's Manual page 67

MERLIN LEGEND Communications System Release 6.0
System Manager's Guide 555-660-118
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 your local telephone company central office, ask them
which terms they use for the specific facilities they connect to your system.
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
February 1998
Page 2-15