AT&T Partner II Operating manual

AT&T
PARTNER
®
II Centrex
Communications System
Release 1
Installation and Use

Copyright © 1991 AT&T
All Rights Reserved
Printed in U.S.A.
AT&T 518-455-330
Issue 1
November 1991
Notice
Every effort was made to ensure that the information in this book was complete and accurate at the
time of printing. However, information is subject to change.
Federal Communications Commission (FCC) Interference Notice
This equipment has been tested and found to comply with the limits for a Class A digital device,
pursuant to Part 15 of FCC rules. These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a commercial environment. This equipment
generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful interference to radio communications.
Operation of this equipment in a residential area is likely to cause harmful interference, in which case
the user will have to correct the interference at his or her own expense. For additional FCC
interference, registration, and repair information, see Appendix E of this book.
Trademarks
MLS-34D, MLS-12D, MLS-12, MLS-6, MLC-6, and SYSTIMAX are trademarks of AT&T.
PARTNER, Magic on Hold, MERLIN, and PagePac6 are registered trademarks of AT&T.
ESSX is a registered trademark of Bell South Corporation.
CENTRON is a registered trademark of U S West, Inc.
Plexar is a registered trademark of Southwestern Bell Telephone.
Warranty
AT&T provides a limited warranty to this product. Refer to “AT&T Limited Warranty and Limitation of
Liability” in Appendix C.
Ordering Information
The order number for this book is 518-455-330. To order copies of this book, call 1 800 432-6600 in
the U.S. and 1 800 255-1242 in Canada. For more information on how to order this and other system
reference materials, see “Reference Materials” in “About This Guide.” For information on ordering
replacement parts, accessories, and other compatible equipment, refer to “Product Ordering
Information” in Appendix C.
Support Telephone Numbers
In the U.S., AT&T provides a toll-free customer helpline 24 hours a day. Call the AT&T Helpline at
1 800 628-2888 if you need assistance when installing, programming, or using your premises
equipment.
For assistance in Canada, contact your local AT&T authorized dealer.

Contents
About This Guide
v
1
Overview
1-i
■Terminology
1-1
■Using Premises Equipment to Complement
Centrex Services
1-3
■Primary and Secondary Lines
1-5
Features and Capabilities
1-6
■Premises Equipment
1-7
■
2
Installing the Equipment
2-i
■Important Safety Instructions 2-ii
Terminology
2-1
■
■Installation Guidelines
2-3
■Example Configuration 2-6
■Installation Procedures
2-8
Equipment Upgrades 2-14
■
3
Using the Equipment with Centrex Services
3-i
Overview
3-1 ■
■Terminology
3-2
■Centrex Line Assignments and Ringing 3-3
■Centrex Services
3-5
One-Touch Access to Centrex Services
3-6
■
4
Decisions for Customizing Your System
■Overview
Terminology
■Call Coverage Options■One-Touch Access to Equipment Features
■Optional Features for Premises Equipment
■Auxiliary Equipment
■Identifying the Equipment Features You Need
■
4-i
4-1
4-2
4-3
4-10
4-13
4-22
4-24
Contents i

5
Programming Reference
■Alphabetical List of System and Telephone
Programming Procedures
Overview
■
■Terminology
■System Programming Procedures
■Telephone Programming Procedures
■Changing Settings after Installation
■System Programming Reference
■System Speed Dial Programming Reference
■Telephone Programming Reference
5-i
5-ii
5-1
5-2
5-3
5-4
5-7
5-10
5-14
5-15
6
Using Telephones
Overview ■
■
Terminology
■MLS- and MLC-Model Telephones
■
Standard Telephones
■Combination Extensions
■
Equipment Features
Using Your Telephone
■
6-i
6-1
6-1
6-2
6-7
6-9
6-10
6-12
7
Using Auxiliary Equipment
7-i
■
Terminology
7-1
■
Fax Machines
7-1
■Answering Machines 7-5
■
Modems
7-6
■Credit Card Scanners 7-7
Call Reporting Devices (SMDR)
7-7
■
A
User Forms
A-1
■Form A: Speed Dial Numbers
A-2
Form B: Centrex Extension Numbers
A-3
■
B
Using Intercom Features
B-1
■Using the Intercom on MLS- and MLC-Model
Telephones
B-1
Using Intercom Calling Features
B-3
■
ii Contents

C
Maintenance and Customer Support
C-1
■Maintenance
C-1
■In Case of Difficulty
C-2
Repair Information
■
C-9
■AT&T Limited Warranty and Limitation of Liability
C-9
■Product Ordering Information
C-11
D Specifications
D-1
E
FCC Information
E-1
■
Federal Communications Commission (FCC)
Interference Information
E-1
Feedback Form
GL
Glossary
GL-1
IN
Index
IN-1
Programming Quick Reference
Inside back cover
Contents iii

About This Guide
Purpose
The system described in this guide consists of premises equipment and Centrex
services. Although the terms “premises equipment,” “Centrex services,” and
“system” have broader meanings elsewhere, this guide uses those terms to
refer specifically to the following definitions:
Premises equipment refers to the AT&T equipment controller and MLS- ■
and MLC-model telephones that you purchased as part of your Partner®
II Centrex Communications System, plus all other telecommunications
devices connected to your equipment controller. This equipment is
installed at your place of business.
■ Centrex services include the Centrex lines that are connected to the
equipment controller and the features available on those Centrex lines.
These services (which may be offered in your area under a different name
such as ESSX,® CENTRON,® or Plexar®) must be arranged for
separately with your local telephone company.
■
System refers to the combination of premises equipment and Centrex
services described above.
The main purpose of this guide is to provide instructions for installing,
programming, and using your premises equipment. Because the selection of
services available from the local phone companies continually expands and
changes—to keep pace with the needs of businesses and with technological
advances in the world of communications—this guide does not provide detailed
information about Centrex services. For specific information about your Centrex
services, see the Centrex documentation provided by your local telephone
company.
About This Guide
v

Terminology
The following terms are used throughout this guide, and are important for
understanding how your system works. In addition, each chapter in this guide
begins with a “Terminology” section that defines key terms used in the chapter.
All terms are also defined in the Glossary.
Centrex
Centrex system
Equipment
controller
Equipment
feature
MLS- and
MLC-model
telephones
Premises
equipment
Standard
phone
System
Telephone services that your local telephone company
provides from a Central Office (CO) located outside your
business premises, including Centrex lines connected to the
equipment controller and the features available on those
Centrex lines. (Your telephone company may call Centrex by
another name.)
The total block of Centrex lines you subscribe to—all or some
of which may be connected to the equipment controller for
your system—together with the Centrex services associated
with those lines. See also Premises equipment and System.
The AT&T product that you purchased as part of your
system. This product consists of a group of modules that
connect Centrex lines coming into your building to the
extensions in your system. The equipment controller also
provides equipment features.
A feature provided by your equipment controller (as opposed
to a service provided by Centrex).
The AT&T telephones that you purchased as part of your
system. These telephones are specifically designed for use
with the equipment controller. Models include the MLS-34D™
telephone, MLS-12D™ telephone, MLS-12™ telephone,
MLS-6™ telephone, and MLC-6™ telephone.
The AT&T equipment controller and the MLS- and
MLC-model telephones that you purchased as part of your
system, plus all other telecommunication devices that are
connected to your equipment controller. For purposes of this
guide, premises equipment does not include any equipment
that connects directly to Centrex lines without going through
the equipment controller. See also System and Centrex
system.
An industry-standard touch-tone or rotary phone such as you
might have in your home. Some standard phones include
special feature buttons for frequently-used calling functions.
Your premises equipment, in combination with the Centrex
lines that are connected to your equipment controller and the
Centrex services that are available on those lines. See also
Centrex system and Premises equipment.
vi About This Guide

How to Use This Guide
This guide provides instructions and advice on the following topics:
■
■
Installation. If you are installing the system for the first time, read
Chapters 1 and 2 and Appendix D, which provide an overview of the
system, instructions for equipment installation, and equipment
specifications.
If your company already has modular jacks for all outside lines and
extensions, you may be able to use the existing wiring to install the
equipment controller and connect telephones yourself (see Chapter 2).
If you prefer to have an AT&T service technician install and customize
your premises equipment, call 1 800 247-7000 (in the U.S. only) or
your AT&T authorized dealer.
Your system can include a wide variety of auxiliary equipment,
including fax machines, modems, answering machines, credit card
scanners, and call reporting (SMDR) devices. See Chapter 7 for
advice on setting up these industry-standard devices to work
effectively with your system.
Setup Decisions. If you are a new user, read Chapters 1, 3, 4, and 6, to
familiarize yourself with the features provided by your equipment
controller, to learn how to program the equipment controller and
individual phones, and to learn how to handle calls.
Chapter 3 explains how your equipment controller complements
Centrex services, providing a variety of features that support Centrex
capabilities and making it easy for you to access Centrex features.
Chapter 4 helps you make decisions about customizing the premises
equipment, to use additional features and capabilities provided by
your equipment. Chapter 6 provides call-handling instructions for
standard phones and for MLS- or MLC-model phones.
Programming. Chapter 5 gives step-by-step instructions for all of the
programming procedures for your premises equipment. You can use the
information in this chapter as a reference, to help you carry out your
decisions about customizing your premises equipment.
Making Changes. If you need to reprogram the premises equipment or
individual extensions, see Chapter 5, “Programming Reference,” or the
Programming Quick Reference pages at the back of this book.
If you are adding equipment to your system, see Chapter 2, “Installing
the Equipment,” Chapter 5, “Programming Reference,” and Chapter 7,
“Using Auxiliary Equipment.”
Training Co-Workers. Chapter 6 explains how to handle calls and use
equipment features effectively. To help users get the most out of their
phones, give each telephone user a Quick Reference card and filled-in
copies of the “Speed Dial Numbers” form in the System Planner or
Appendix A of this book.
■
■
■
About This Guide vii

Before training co-workers, read Appendix B to decide whether to
make intercom calling features available to telephone users. (These
equipment features require that users know the jack numbers where
lines and extensions are connected to the equipment controller.) In
addition, panels 6 and 7 of the Quick Reference card present intercom
calling features.
Solving Problems. Appendix C provides information on solving
problems and ordering additional accessories and equipment. If your
premises equipment malfunctions, you may be able to solve the problem
by following the steps provided in “Troubleshooting,” starting on page
C-3.
Daily Operation. Depending on how your system is set up, you may
■
■
need to oversee some of the system’s daily operations. For example, if
you use the Night Service feature available with your equipment
controller, you will need to turn on Night Service at the end of each day
before leaving the office. (See “Using Night Service” on page 6-18.)
Once you are experienced with the system, use the Table of Contents or Index
to locate the information you need.
Product Safety Labels
This book contains several product safety statements, identified by a
CAUTION:
Indicates the presence of a hazard that will or can cause minor personal
injury or property damage if the hazard is not avoided.
WARNING:
Indicates the presence of a hazard that can cause severe or fatal
personal injury if the hazard is not avoided.
Carefully read the
WARNING statement on page 2-9. Opening the
equipment modules or backplane will expose you to hazardous voltages, which
can cause severe personal injury or death. Also, read “Important Safety
Instructions” on page 2-ii before performing any installation procedures.
Reference Materials
The following reference materials are available to help you install, program, and
use the premises equipment. To order them, call the AT&T Customer
Information Center (1 800 432-6600 in the U.S. or 1 800 255-1242 in Canada).
The order numbers are in parentheses:
■
■
Installation and Use (518-455-330) provides instructions for installing,
programming, and using the premises equipment.
Quick Reference for Use with MLS-Series Telephones (518-455-331,
package of 6) contains basic instructions for using MLS-model
telephones.
viii About This Guide

■
MLC-6 Cordless Telephone: Installation and Troubleshooting
(999-506-143) explains how to install the MLC-6 cordless telephone and
how to solve any problems that might occur when using it with your
system.
MLC-6 Cordless Telephone Quick Reference: Display and Controls
■
(999-506-146) explains how to use the MLC-6 cordless telephone with
your system.
In addition, a System Planner (GBS-124) provides forms that you should use
before you install your system—to determine your system configuration—and on
an ongoing basis—to make sure that you have a current record of all the
programming for your premises equipment. You can order the Planner from
AT&T Forms Services at 1 800 367-6487.
How to Comment on This Guide
A feedback form is located at the end of this guide, after the appendixes. Use
that form to send AT&T your comments on the product or this guide, or send
your comments and recommendations for changes to:
A. Sherwood
AT&T
99 Jefferson Road (Room 2A-25)
Parsippany, NJ 07054
(FAX [phone])
About This Guide ix

Overview
1
Contents
Terminology
1-1
Using Premises Equipment to Complement
Centrex Services
1-3
Primary and Secondary Lines
1-5
Features and Capabilities
1-6
Premises Equipment
1-7
■Equipment Controller
1-8
Modules
1-8
Capacity
■MLS- and MLC-Model Telephones
■Auxiliary Equipment
Industry-Standard Devices
Other Devices
1-8
1-9
1-9
1-10
1-11
Overview 1-i

Overview
1
Terminology
The following terms are used in this chapter. In addition, you may wish to review
the “Terminology” section of “About This Guide,” which defines basic terms
used throughout this guide, or the Glossary, which defines all terms.
Auto Dial
button
Auxiliary
equipment
Centrex
Centrex
extension
number
Centrex system
A programmable telephone button that lets you dial a series
of digits simply by pressing that button. An Auto Dial button
can be used to store a Centrex feature code or a telephone
number so that it can be dialed with one touch.
Telecommunications equipment (other than MLS- and
MLC-model telephones) that can be connected to the
equipment controller. Auxiliary equipment includes
industry-standard devices that can connect directly to the
public telephone network (such as standard phones or fax
machines) as well as devices that require the interface
provided by the equipment controller (such as a loudspeaker
paging system).
Telephone services that your local telephone company
provides from a Central Office (CO) located outside your
business premises, including Centrex lines connected to the
equipment controller and the features available on those
lines. (Your telephone company may call Centrex by another
name.)
A short code (or “Centrex extension ID”) that can be used to
dial another extension within the Centrex system. Typically,
this is the last digits of the Centrex telephone number.
The total block of Centrex lines you subscribe to—all or some
of which may be connected to the equipment controller for
your system—together with the Centrex services associated
with those lines.
Overview 1-1

Equipment
Controller
Equipment
feature
Equipment
feature
button
Extension
Extension jack
Feature phone
Intercom call
Premises
equipment
Primary line
Programmable
button
Secondary line
Standard
phone
1-2 Overview
The AT&T product that you purchased as part of your
system. This product consists of a group of modules that
connect Centrex lines coming into your building to the
extensions in your system. The equipment controller also
provides equipment features.
A feature provided by your equipment controller (as opposed
to a service provided by Centrex).
A programmable telephone button on an MLS- or MLC-model
telephone that enables you to access an equipment feature
with one touch, simply by pressing the button. See also Auto
Dial button and Programmable button.
A destination in the system that can be dialed.
The location on 206 modules that allows you to connect
phones (or other telecommunications devices) to the
equipment controller.
An industry-standard phone that includes programmable
buttons or other built-in features.
A call that is made using the [
Intercom ] button on an MLS- or
MLC-model telephone, to call another system extension
without tying up primary Centrex lines.
The AT&T equipment controller and MLS- and MLC-model
telephones that you purchased as part of your system, plus
all other telecommunications devices that are connected to
your equipment controller. For purposes of this guide,
premises equipment does not include any equipment that
connects directly to Centrex lines without going through the
equipment controller. See also System and Centrex system.
The main Centrex line assigned to an extension, generally
used to place and receive all calls for that extension. When a
caller dials a phone number, the call rings immediately at the
extension where the line is assigned as a primary line (unless
line ringing is changed to let another extension screen calls
on the line). See also Secondary line.
A telephone button that can be set up to access a feature.
On MLS- and MLC-model phones, programmable buttons
can be used as Auto Dial buttons (for one-touch dialing of
Centrex feature codes or telephone numbers) or equipment
feature buttons.
A line assigned to an extension for call coverage purposes,
generally with delayed or no ringing. When a call comes in
on the line, it rings first at the extension where it is assigned
as the primary line; only if there is no answer does it ring at
the extension where it is a secondary line. See also Primary
line.
An industry-standard touch-tone or rotary phone such as you
might have in your home. Some standard phones include
special feature buttons for frequently-used calling functions.

System
Your premises equipment, in combination with the Centrex
lines that are connected to your equipment controller and the
Centrex services that are available on those lines. See also
Centrex system and Premises equipment.
Using Premises Equipment
to Complement Centrex Services
The system discussed in this guide consists of two elements: Centrex services
(including Centrex lines and associated features) and premises equipment
(including the equipment controller, MLS- and MLC-model telephones, and
other telecommunications devices connected to the controller).
The Centrex services you receive from your local telephone company provide a
unified telephone network for your business, even across different geographical
locations, and give you services customized for your needs.
NOTE:
Your telephone company may offer Centrex services under a different name (for
example, ESSX,® CENTRON,® or Plexar®). Also, you may be able to select
different services for different lines. (For more information, see the Centrex
documentation provided by your local telephone company.)
Your AT&T premises equipment is designed to complement the advantages
offered by Centrex. All or some of your Centrex lines may be connected to the
equipment controller. You can connect a maximum of 24 Centrex lines and 24
extensions to your equipment controller. Figure 1-1 shows an example in which
some Centrex lines are connected to the equipment controller and some are not
Public Phone
Network
Centrex
Central
Office
Your Centrex System
Your System
Equipment
Controller
555-1000
555-1001 555-1002
555-1003 555-1004
555-1005
Figure 1-1. Your Centrex System
Overview 1-3

Any Centrex lines that are not connected to the equipment controller, while they
are part of the larger Centrex system, are not considered to be part of the
system described in this guide. For example, a hospital might subscribe to a
large block of Centrex lines, but connect only the lines for administrative
personnel to the equipment controller. In this situation, the telephones for
administrative personnel would be managed by the equipment controller as a
distinct system within the larger Centrex system.
One of the most important Centrex features is the assignment of one Centrex
line for each extension in your system. This allows a caller to reach an extension
directly, simply by dialing the extension’s phone number, as shown in Figure
1-2. The call rings at the extension immediately, so you do not need to have a
receptionist who answers calls for all system extensions and then transfers each
call to the appropriate user.
Public Phone
Network
Centrex
Central
Office
Caller dials 555-1002
Equipment
Controller
555-1000
555-1001
555-1003 555-1004 555-1005
Ringing
Figure 1-2. Dialing a System Extension
The equipment controller complements Centrex by automatically assigning a
primary line to each extension (see “Primary and Secondary Lines” on the next
page), and by passing Centrex ringing patterns through to phones. (The major
benefits provided by your equipment controller and the AT&T phones that you
connect to it are discussed in “Features and Capabilities” on page 1-6; in
addition, Chapter 3 provides a more detailed discussion of the way your
premises equipment and Centrex services work together.)
The equipment controller also provides optional features, some of which may be
similar to Centrex services you have. (Optional equipment features are listed at
the end of Chapter 4 in this guide.) If you have similar features available from
Centrex and from the equipment controller, you should use the Centrex features.
NOTE:
The System Planner, available separately, provides forms you can use to plan
your system configuration and to identify your Centrex services. If you do not
already have a copy of the System Planner, see “Reference Materials” in “About
This Guide.”
1-4 Overview

Primary and Secondary Lines
By default, each extension in your system gets one primary line that will be used
to receive and place all calls for that extension. When the user at an extension
picks up the handset to make an outgoing call, the primary line for the extension
is automatically selected. Likewise, all incoming calls on the primary line ring
immediately at the user’s phone. The primary line always appears on the bottom
leftmost line button on an MLS- or MLC-model phone. Except for Hotline phones
and doorphones (see page 4-23), each extension in your system has a primary
Centrex line.
You can also assign secondary lines to extensions. Secondary lines are lines
other than the primary line, typically assigned to a phone for call coverage
purposes. Secondary lines generally use delayed ringing; when a call comes in
on a line, it rings first at the extension where the line is assigned as a primary
line; only after about 20 seconds does it begin ringing at an extension where it is
assigned as a secondary line. Likewise, when a user picks up the handset to
make an outgoing call, the extension’s primary line is selected automatically. A
secondary line is selected automatically only to answer an incoming call (if the
call is already ringing at your phone when you pick up the handset).
All lines are automatically assigned to the first phone connected to the
equipment controller; but only the line assigned to the bottom leftmost line
button on the phone is primary. All of the other lines assigned to the extension
are secondary lines. (This default line arrangement provides Central Call
Coverage; for more information about this and other call coverage options, see
page 4-3.)
NOTE:
Secondary lines assigned to an extension are used as primary lines at other
extensions. To avoid tying up another user’s primary line, callers who have
secondary lines should always use their own primary lines to make outgoing
calls.
Overview 1-5

Features and Capabilities
Your equipment controller supports the following features to complement your
Centrex services:
■
■
■
Multiple line assignments, permitting more flexible call coverage. For
example, the equipment controller automatically assigns all lines to the
first phone connected to the equipment controller, to serve as a possible
receptionist’s position. In addition, you have the option of assigning
secondary lines at other phones, to provide Local Call Coverage, so that
a person can answer calls on a line when the line’s primary user is absent
or busy. The equipment controller also passes Centrex ringing patterns
through to each phone (for example, to distinguish between outside and
inside calls). When a line is assigned to an MLS- or MLC-model phone,
the lights on the line button let you see the activity on the line.
Programmable buttons on MLS- and MLC-model phones, providing
one-touch access to both Centrex and equipment features). You can
access a feature simply by pressing the button.
Easy-to-use programming procedures, making it easy for you to manage
your system. You can change line assignments, call coverage
arrangements, or programmable buttons, quickly and easily. (The display
on an MLS-34D or MLS-12D phone provides feedback during
programming.)
Modular connections to the equipment controller, making it easy for you
to reconfigure your system or to add extensions as your system grows.
Direct connections for industry-standard devices—including standard
phones, fax machines, answering machines, modems, and credit card
scanners.
Optional equipment features, including paging over a loudspeaker
paging system or over MLS-model phone speakers, music on hold*, call
detail recording (also known as Station Message Detail Recording, or
SMDR), night service operation, speed dialing, line access restrictions,
and many others.
Power failure operation with standard phones, allowing you to make and
■
■
■
■
answer calls during a power failure while retaining programmed
equipment settings for up to four days. (An optional Uninterruptible
Power Supply, or UPS, is also available to allow full equipment operation
during a power failure.)
*
If you use equipment that rebroadcasts music or other copyrighted materials, you may be required to obtain
a license from a third party such as ASCAP or BMI. Or, you can purchase a Magic on Hold® device from
AT&T that does not require you to obtain such a license.
1-6 Overview

Premises Equipment
Figure 1-3 shows an equipment controller and MLS- and MLC-model telephones
connected to it. A brief description of each component follows the figure.
EQUIPMENT CONTROLLER
(covers not shown)
206 Module
Circuit Breakers
Primary
Carrier Expansion Carrier
Main Circuit
Breaker Main Circuit
Breaker
206 Modules
400 Modules
Primary
Processor Module
Expansion
Processor
Module
Line Jacks
Line Jacks
Power Indicators
(LEDs)
PAGE Jack
SMDR Jack
Extension Jacks
(206 modules only)
MUSIC ON HOLD Jack
(for RCA phono plug)
Expansion
Cable
Power Indicators
(LEDs)
PHONES
MLS-34D
Display Phone
MLS-12D
Display Phone
MLS-12
Phone
MLS-6
Phone
Wall Jacks
MLC-6
Cordless Phone
Figure 1-3. Equipment Controller and MLS/MLC-Model Telephones
Overview 1-7

Equipment Controller
The equipment controller is the heart of your premises equipment. It is made up
of one or two carriers — the plastic housing consisting of the backplane and
cover. The backplane distributes power to the premises equipment, and has
slots where modules are placed; the cover slides onto the front of the backplane
after all the modules have been installed.
The system must have a primary carrier for support of up to 12 lines and
extensions, and can be expanded to include an expansion carrier for support of
up to 12 more lines and extensions. A fully loaded system has both carriers.
Modules
The following modules are installed in your equipment controller:
■
■
Primary processor module. The primary processor module manages
the components of your premises equipment. It has jacks for a
music-on-hold audio source, a loudspeaker paging system, and a call
reporting device (SMDR), such as a printer. The primary processor
module is always installed in the center slot of the primary carrier.
Expansion processor module. (optional) The expansion processor
module extends the primary processor module’s management
capabilities to the lines and extensions connected to modules in the
expansion carrier. An expansion cable connects the primary processor
module to the expansion processor module. This module is always
installed in the center slot of the expansion carrier.
206 Modules. Each 206 module connects a maximum of two Centrex
lines and six extensions to the equipment controller. You can connect
telephones and other telecommunications devices (such as fax
machines, answering machines, or modems) to the extension jacks on
the 206 module (either directly or through your building’s extension
jacks). Each 206 module has a green power indicator that shows it is
receiving power from the equipment controller. At least one 206 module
is required in the leftmost slot of the primary carrier.
400 Module. The 400 module is similar to the 206 module, but without
■
■
extension jacks. It has jacks for four Centrex lines. The 400 module is
always installed to the right of a 206 module.
Capacity
The number of 206 and 400 modules you install in the equipment controller
determines the number of available lines and extensions. The controller
implements the Centrex requirement of one line for each extension. Therefore,
when you install a 400 module (four lines) next to a 206 module (two lines, six
extensions) in a carrier, the combined pair provides an equal number (six) of
lines and extensions. For the maximum number of lines and extensions in a
two-carrier configuration, pair four 206 modules with four 400 modules—for a
total of 24 lines and 24 extensions.
1-8 Overview

MLS- and MLC-Model Telephones
AT&T MLS- and MLC-model telephones are designed to make maximum use of
the features provided by your system. The following models are available for use
with your system:
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AT&T MLS-34D Telephone. This phone is the best choice for extensions
used by the system manager (for equipment programming), receptionist,
or operator. It has 32 buttons that can be used for outside lines or
programmed for one-touch access to features. It also has a built-in
speaker and microphone (for dialing and having a conversation without
lifting the handset) and a large character display that shows the following:
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Current date, day, and time
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Number you dialed and elapsed time (when you make a call)
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Prompts and messages.
AT&T MLS-12D Telephone. This phone has 10 buttons that can be used
for outside lines or programmed for one-touch access to features (and 6
more buttons without lights that can only be used for programmable
features). It has a built-in speaker and microphone, and a display similar
to the one on the MLS-34D telephone.
NOTE:
An MLS-34D or MLS-12D telephone is required for equipment programming.
Use the MLS-12D phone only if there are no MLS-34D phones installed at the
site.
AT&T MLS-12 Telephone. This telephone has all the features of the
MLS-12D telephone, but without a display.
AT&T MLS-6 Telephone. This phone has 4 buttons that can be used for
outside lines or programmed for one-touch access to features. It also has
a built-in speaker, but no microphone. This means that a user can dial a
number without lifting the handset, but must lift the handset to speak
when the party answers.
AT&T MLC-6 Cordless Telephone. This cordless telephone works like
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the MLS-6 corded telephone. It has 4 buttons that can be used for
outside lines or programmed for one-touch access to features. It also
includes a display that shows line status, an On/Off button that must be
pressed before using the phone (to save battery power), and additional
feature buttons to support cordless operation (for more information, see
MLC-6 Cordless Telephone Quick Reference: Display and Controls).
Auxiliary Equipment
The premises equipment works with many telecommunications devices, not only
MLS- and MLC-model telephones. You can connect industry-standard devices
to your equipment controller, and certain models of other devices, all without
expensive adapters.
Overview 1-9