ATT System 25 Reference Manual

							AT&T 555-540-200
Issue 1, September 1989
AT&T System 25
Release 3, V 3
Reference Manual 
						

							TO ORDER COPIES OF THIS MANUAL (INCLUDES ADDENDUM)
Call: AT&T Customer Information Center on 1-800-432-6600
In Canada Call 1-800-255-1242
Write: AT&T Customer Information Center
2855 North Franklin Road
P.O. Box 19901
Indianapolis, IN 46219-1385
TO COMMENT ON THIS ADDENDUM
Call: The AT&T Document Development Organization
Hot Line: 1-800-334-0404
In North Carolina Call (919) 727-6681
While reasonable efforts were made to ensure that the information
in this document was complete and accurate at the time of printing,
AT&T can assume no responsibility for errors. Changes or
corrections to the information in this document may be incorporated
into future reissues.
Published by
The AT&T Documentation
Development OrganizationCopyright© 1991 AT&T
All Rights Reserved
Printed in U.S.A. 
						

							FCC NOTIFICATION AND REPAIR INFORMATION
AT&T SYSTEM 25
This telephone equipment is registered with the Federal Communications Commission (FCC) in
accordance with Part 68 of its Rules. In compliance with the Rules, be advised of the following:
MEANS OF CONNECTION
Connection of this telephone equipment to the nationwide telecommunications network shall be
through a standard network interface USOC RJ21X jack. Connection to private line network
channels requires USOC RJ2GX jack for tie lines or USOC RJ21X jack for off-premises station
lines. Connection to T1 facilities requires USOC RJ48X jack. These can be ordered from your
telephone company.
NOTIFICATION TO THE TELEPHONE COMPANY
If the system is to be connected to off-premises stations (OPSs), you must notify the telephone
company of the OPS class of service, OL13C, and the service order code, 9.0F. For R3 systems,
the analog service code is 9.0Y and the digital service order code is 6.0Y.
Upon the request of the telephone company, inform them of the following:
— The Public Switched Network “lines” and the Private “lines” to which you will connect the
telephone equipment.
— The telephone equipment’s “registration number” and “ringer equivalence number” (REN)
from the label on the equipment.
— For private line connections, provide the facility interface code, TL31M for tie lines. You
must also specify the service order code, 9.0F or 9.0Y for R3 systems.
— For digital connections with D4 Framing Format provide the Facility Interface Code 04DU9-
B or for digital connections with Extended Framing Format the interface code is 04DU9-C.
You must also specify the service order code, 6.0Y.
— The quantities and USOC numbers of the jacks required.
— For each jack, provide the sequence in which lines are to be connected; the type lines and
the facility interface code and the ringer equivalence number by position, when applicable.
This telephone equipment should not be used on coin telephone lines. Connection to party line
service is subject to state tariffs.
November 1995 
						

							REPAIR INSTRUCTIONS
If you experience trouble with this telephone equipment, contact the AT&T National Service Center
on 1-800-628-8888. The Telephone Company may ask that you disconnect this equipment from the
network until the problem has been corrected or until you are sure that this equipment is not
malfunctioning.
RIGHTS OF THE TELEPHONE COMPANY
If your telephone equipment causes harm to the telephone network, the Telephone Company may
discontinue your service temporarily. If possible, they will notify you in advance. But if advance
notice is not practical, you will be notified as soon as possible. You will be informed of your right to
file a complaint with the FCC.
Your Telephone Company may make changes in its facilities, equipment, operations or procedures
that could affect the proper functioning of your equipment. If they do, you will be notified in advance
to give you an opportunity to maintain uninterrupted telephone service.
HEARING AID COMPATIBILITY
The voice terminals described in this manual are compatible with inductively coupled hearing aids
as prescribed by the FCC.
FCC INFORMATION
FCC REGISTRATION INFORMATION
Registration NumberAS593M-71565-MF-E
Ringer Equivalence0.5A
Network InterfaceRJ21X, RJ2GX or RJ48X
PRIVATE LINE SERVICE
Service Order Code
l Analog9.0F
l Analog (R3)9.0Y
l Digital (R3)6.0Y
Facility Interface Code
l Tie LinesTL31M
l Off-Premises StationsOL13C
l Digital D4 Framing04DU9-B
l Digital ESF04DU9-C
November 1995 
						

							FCC WARNING STATEMENT
Federal Communications Commission (FCC) Rules require that you be notified of the following:
l This equipment generates, uses, and can radiate radio frequency energy and, if not installed
and used in accordance with the instruction manual, may cause interference to radio
communications.
l It has been tested and found to comply with the limits for a Class A computing device pursuant
to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protection
against such interference when operated in a commercial environment.
l Operation of this equipment in a residential area is likely to cause interference in which case the
user at his or her own expense will be required to take whatever measures may be required to
correct the interference.
SECURITY OF YOUR SYSTEM—PREVENTING TOLL FRAUD
As a customer of a new telephone system, you should be aware that there exists an increasing
problem of telephone toll fraud. Telephone toll fraud can occur in many forms, despite the
numerous efforts of telephone companies and telephone equipment manufacturers to control it.
Some individuals use electronic devices to prevent or falsify records of these calls. Others
charge calls to someone else’s number by illegally using lost or stolen calling cards, billing
incorrect parties, clipping on to someone else’s line, and breaking into someone else’s telephone
equipment physically or electronically.In certain instances, unauthorized individuals make
connections to the telephone network through the use of remote access features.
The Remote Access feature of your system, if you chose to utilize it, permits off-premises callers
to access the system from a remote telephone by using an 800 number or a 7- or 10- digit
telephone number. The system returns an acknowledgement signaling the user to key in his or
her authorization code, which is selected and administered by the system manager. After the
authorization code is accepted, the system returns dial tone to the user. If you do not program
specific egress restrictions, the user will be able to place any call normally dialed from a
telephone associated with the system. Such an off-premises network call is originated at, and
will be billed from, the system location,
The Remote Access feature, as designed, helps the customer, through proper administration, to
minimize the ability of unauthorized persons to gain access to the network. Most commonly,
phone numbers and codes are compromised when overheard in a public location, through theft
of a wallet or purse containing access information, or through carelessness (writing codes on a
piece of paper and improperly discarding it). Additionally, hackers may use a computer to “dial”
an access code and then publish the information to other hackers. Enormous charges can be
run up quickly. It is the customer’s responsibility to take the appropriate steps to properly
implement the features, evaluate and administer the various restriction levels, protect access
codes, and distribute access codes only to individuals who have been fully advised of the
sensitive nature of the access information. 
						

							Common carriers are required by law to collect their tariffed charges. While these charges are
fraudulent charges made by persons with criminal intent, applicable tariffs state that the customer
of record is responsible for payment of all long-distance or other network charges. AT&T cannot
be responsible for such charges and will not make any allowance or give any credit for charges
that result from unauthorized access.
To minimize the risk of unauthorized access to your communications system:
l
l
l
l
l
l
l
l
lUse a nonpublished Remote Access number.
Assign authorization codes randomly to users on a “need-to-have” basis, keeping a log
of ALL authorized users and assigning one code per person.
Use random sequence authorization codes, which are less likely to be broken.
Deactivate all unassigned codes promptly.
Ensure that Remote Access users are aware of their responsibility to keep the telephone
numbers and any authorization codes secure.
When possible, restrict the off-network capability of off-premises callers, via use of Call
Restrictions and Disallowed List capabilities.
When possible, block out-of-hours calling.
Frequently monitor system 
call detail reports for quicker detection of any unauthorized or
abnormal calling patterns.
Limit Remote Call Forward to persons on a “need-to-know” basis.
DANGER
The AT&T System 25 cabinets are not user serviceable.
Some voltages inside the cabinets are hazardous. This
equipment is to be serviced only by qualified technicians. 
						

							CONTENTS
CONTENTS
Section 1—Overview
Section 2—Features and Services
Section 3—Functional Description
Section 4—Hardware Description
Section 5—Technical Specifications
Section 6—Environmental Requirements
Section 7—Parts Information
Section 8—Reference Documentation
Section 9—Glossary
Section 10—Index 
						

							OVERVIEW
Introduction
Organization
System 25 Description
Call Handling Capabilities
Safety
Business Communications Needs
Incoming Business Communications
Outgoing Business Communications
Internal Call Movement
Data Communications
Growth & Rearrangement
Conclusions
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							Figures
Figure 1-1.System 25 Block Diagram                                                                                     1-2
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							OVERVIEW
OVERVIEW
Introduction
This reference manual provides general technical information on AT&T System 25 (System
25). It includes a description of the system, its hardware and software, features and
services, environmental requirements, and technical specifications. This manual is intended
to serve as an overall technical reference for System 25.
This manual is released specifically to cover Release 3 (R3) of System 25. It does not
contain information that applies only to the earlier releases of System 25.
In System 25 documentation, the terms “voice terminal,” “voice stations,” and “telephones”
are used to describe the same piece of equipment. In addition the term “multiline voice
terminal”includes the“ATL Cordless Telephone,”
unless the reference is specifically
restricted to corded multiline voice terminals only. The System 25 documentation also uses
the terms “Personal Dial Code (PDC),” “extension,”or “extension number” interchangeably.
Organization
This manual is divided into 10 sections. The remaining sections are as follows:
l SECTION 2—FEATURES AND SERVICES
l SECTION 3—FUNCTIONAL DESCRIPTION
l SECTION 4—HARDWARE DESCRIPTION
l SECTION 5—TECHNICAL SPECIFICATIONS
l SECTION 6—ENVIRONMENTAL REQUIREMENTS
l SECTION 7—PARTS INFORMATION
l SECTION 8—REFERENCE DOCUMENTATION
l SECTION 9—GLOSSARY
l SECTION 10—INDEX.
System 25 Description
System 25 is an advanced digital switching system that integrates voice and data
communications. (See block diagram in Figure 1-1.) It not only provides the features of a
state-of-the-art Private Branch Exchange (PBX), but goes a step further by allowing data to
be switched point-to-point without first being converted to analog format. This capability can
1-1