Lucent Technologies MERLIN LEGEND System Manager's Manual page 74

MERLIN LEGEND Communications System Release 5.0
System Manager's Guide 555-650-118
3 System Components
Control Unit
NOTE:
The MERLIN LEGEND MAIL® Voice Messaging System integrates a T/R
module with a voice messaging system and is both a module and an
application.
Modules Supporting Lines/Trunks
Table 3–1
describes a few module features and modules that need additional explanation.
NOTE:
Modes of operation affect features and hardware. For example, Direct
Inward Dial is supported only in Hybrid/PBX mode, so if your system uses
a different mode of operation, you do not need a DID module. For more
information about modes, see
Power-Failure Transfer Telephones
When your system was planned, the Lucent Technologies representative(s) made
sure that you had a module to support one or more power-failure transfer (PFT)
telephones. These telephones, which are connected to a special line/trunk jack,
allow you to make and receive calls during a commercial power failure. They do
not affect the capacity of the modules.
100D Module
The 100D module has only one line/trunk (called a Digital Signal Level 1 or DS1
facility) but actually supports 23 or 24 "virtual" lines/trunks. These are called
channels or B-channels , depending upon the type of service you choose. As
described in
provide either T1 or Primary Rate Interface (PRI) service on the 100D module.
NOTE:
The 100D module is not available in Behind Switch mode.
In addition, PRI and T1 support Group IV (G4) fax machines as well as desktop
and group videoconferencing.
PRI and T1 differ in some important ways:
Primary Rate Interface (PRI). PRI supports Integrated Services Access,
also called Shared Access for Switched Services (SASS) and Call-by-Call
Service Selection . This feature, available from various telecommunications
companies, allows multiple PRI services to use the same facilities,
eliminating the need to have dedicated, separate incoming and outgoing
B-channel groups. It selects the optimal service for each outgoing call,
allowing more than one service over each B-channel, including digital data
communications at speeds up to 64 kilobits per second.
summarizes the modules that support lines/trunks. This section
Chapter 2, ''About the
3
Chapter 2, ''About the
System'', you can program the DS1 facility to
Issue 1
June 1997
Page 3-7
System''.
3
3