AT&T Bell System 1A1 Connection Manual

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BELL SYSTEM PRACTICES
Station Operations Manual
Maior Station Systems
SECTION C71.355
Issue 1, March, 1957
AT&TCo Standard
1A1 KEY TELEPHONE SYSTEM
CONNECTION DATA
DESCRIPTION AND USE
1.00 GENERAL
1 .01
This section describes the content, arrange-
ment, and use of Sections C71.355 through
C71.411, which provide connection data for the lAl
key telephone system. It includes reference informa-
tion and definitions of terms and abbreviations for
these sections. It should be read thoroughly and under-
stood completely before using the index and connec-
tion tables in Sections C71.355 through C71.441.
1.02 Before using' Sections C71.381 thr~ugh
C71.441, a general knowledge of the following
sections is advantageous: C53.151, lAl Key Tele-
phone System, Description; C53.152, lA and lAl Key
Telephone Systems, Supplies; C53.158, lAl Key Tele-
phone System, Installation; C53.159, lAl Key Tele-
phone System, Maintenance; and C53.506, Equip-
ment Cabinets, Apparatus Mountings and Boxes,
Description and Supplies.
1.03 The information contained in Sections C7 l.355
through C71.441 is divided into nine main
groups, each consisting of one or more sections.
• Index.
• Connection data-description and use.
• Power wiring.
• Key telephone unit groupings.
• Cutoff and exclusion.
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11 15
• Key telephone sets-440, 460, 540, 560 series.
• Signal-key and buzzer circuits.
• Separately mounted keys.
• Lamp resistor units.
Each connection data section contains all information,
other than power, . pertaining to the feature which it
covers. Power data for all sections is covered in Sec-
tion C71.383, lAl Key Telephone System, Power Wir-
ing; Section C71.381, lAl Key Telephone System
Typical lA 1 Installations, Condensed Connectio~
Charts, contains two typical installations.
1.04 The connection data in these sections is
furnished for a maximum of six pickup lines
and/or five pickup and hold lines per station.
1.05
The connection data covers key and running
cable assignments, which are of two basic
types.
• Standard Assignments:
Key and running cable
assignments which are covered in these sec-
tions and will meet the requirements of the
majority of installations using the lAl key
telephone system.
• Tailor-made Assignments:
Running cable
assignments which must be made especially fot
a system requiring circuit and feature arrange-
ments rarely used, because of a customer's spe-
cial requirements.
1 .06 There are a number of features available in
the lA 1 key telephone system which are not
used in the majority of installations. These features
include dial selective intercom lines, signal-key and
buzzer circuits, sixth line circuits, exclusion, and
manual and automatic cutoff. Connection data has
been provided for all these features and is covered in
appropriate sections. Because more than one of these
features is rarely provided in any one installation and
in order to effect an economy in the size of running
cables required, the same running cable pairs have
been assigned to more than one feature. These assign-
ments are shown in Table 55.01.
· Copyright,
1957, by American Telephone
and Telegraph Company
Printed in U.S. A. Page 1