Instruction manual

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:
● 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.
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