Lucent Technologies 5 manual Modules Supporting Lines/Trunks, Power-Failure Transfer Telephones

MERLIN LEGEND Communications System Release 5.0	Issue 1
System Manager’s Guide 555-650-118	June 1997

3System Components

Control Unit Page 3-7

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 3

Table 3–1 summarizes the modules that support lines/trunks. This section 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 Chapter 2, ‘About‘ the System’’.

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 Chapter 2, ‘About‘ the System’’, you can program the DS1 facility to 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.