ATT System 25 Reference Manual

System Administration
LEGEND:
B1 –
C1 –
C2 –
W1 –
Z3A1 ADU –C3 –355AF ADAPTER –Z3A4 ADU –C1 –
C7 –
248B ADAPTER –
400B2 ADAPTER –
2012D TRANSFORMER –
* MAY NEED LOCAL POWER† FURNISHED BY INSTALLER
Figure 2-59.
TYPICAL-103A CONNECTION BLOCK†MODULAR CORD (D8W-87) - PEC 2725-07G
OCTOPUS CABLE (WP90780) - PEC 2720-05P
4-PAIR INSIDE WIRING CABLE†
EQUIPPED WITH 3-FOOT PLUG-ENDED EIA CORD - PEC 2169-001
EIA CROSSOVER CABLE (M7U-87)
RS-232 RECEPTACLE TO MODULAR JACK
EQUIPPED WITH 3-FOOT RECEPTACLE-ENDED EIA...

Features and Services
LEGEND:
C1 –
C2 –
C3 –
355AF ADAPTER –
MODULAR CORD (D8W-87) - PEC 2725-07G
OCTOPUS CABLE (WP90780) - PEC 2720-05P
EIA CROSSOVER CABLE (M7U-87) - PEC 2724-30C
RS-232 RECEPTACLE TO MODULAR JACK - PEC 2750-A25
Figure 2-60.SAT Off-Premises Direct Connections
2-326November 1995 

System Administration
LEGEND:
C2 - OCTOPUS CABLE (WP90780) - PEC 2720-05P
OPS - OFF-PREMISES STATION
C3 - EIA CROSSOVER CABLE (M7U-87)
355AF ADAPTER - RS-232 RECEPTACLE TO MODULAR JACK
Z3A4 ADU - EQUIPPED WITH 3-FOOT RECEPTACLE-ENDED EIA CORD
C1- MODULAR CORDS (2) (D8W-87)
C7 - MODULAR POWER CORD (D6AP-87)
PEC 62515
248B ADAPTER - MODULARIZES 2012D TRANSFORMER400B2 ADAPTER - POWER ADAPTER2012D TRANSFORMER - 15-18V AC SOURCE
Figure 2-61.SAT Off-Premises
Switched Connections
2-327 

FEATURES AND SERVICES
System Maintenance
Description
The primary objective of System 25 maintenance is to detect, report, and clear troubles as
quickly as possible and with minimum disruption to normal service. This goal is supported
by periodic automatic diagnostic tests and fault detection hardware. System design allows
most troubles to be resolved to the circuit pack level.
System 25 hardware and software are organized as independent units or maintenance
objects. Each maintenance object is normally a...

System Maintenance
If an error that begins as a Transient System Error is verified or reaches a threshold
level of severity, it is reclassified as a Permanent System Alarm.
Transient system errors are stored in the Transient System Error log. The system
can store a combined total of 40 Permanent System Alarms and Transient System
Errors in the error tables.
l Most Recent System Errors:The ten Most Recent System Errors are recorded by
the system, regardless of their level of severity. These are stored in...

FEATURES AND SERVICES
Tandem Trunking
Description
Tandem trunking provides an enhanced networking capability for System 25. With this
feature, tie trunks can be used to call through System 25 to reach another switching system
(CO or PBX). Calls may be completed over on-network or off-network facilities.
To be treated as tandem trunks, tie trunks must be assigned trunk numbers beginning with
the digit 9. Incoming calls on these trunks may route out of System 25 over ground start,
loop start, or tie...

Tandem Trunking
To gain access to an ARS routing facility, the tandem trunk’s “station” FRL must be equal to
or greater than the route’s FRL. Thus, a tandem trunk with a FRL of 0 has the least ARS
privileges, while a FRL of 3 provides the most privileges.
If the restriction level of the
tandem trunk is less than all route FRLs, reorder tone is returned to the calling party.
Dial Access: No toll restriction is provided for tandem trunk calls. However, access to
outgoing facilities can be controlled via...

FEATURES AND SERVICES
Test
Description
This feature provides users of the 7300H series voice terminals the ability to test their
terminals.
Placing the Test/Program (T/P) switch in the“T” position causes all red and green LEDs to
light alternately and the tone ringer to sound.If the terminal has a display module, the
following responses also occur:
l The display shows 16 darkened squares.
l After the Test switch is returned to its normal position, the Local Display alarm clock
produces 3 short beeps....

Third-Party Call Setup
Third-Party Call Setup
Description
The Third-Party Call Setup feature allows a data terminal (the third party) to set up, via
Command Mode, a call between an on-premises voice or data terminal (the source) and
another voice or data terminal (the destination; can be on- or off-premises). Once the call
has been set up, the third-party drops off and is not included in the call.
Each third-party data terminal may be administered to have a particular source terminal
“associated” with...

FEATURES AND SERVICES
example, if the source terminal is restricted to on-premises calls only, a call to an off-
premises destination terminal will be blocked.
Setting Up A Third-Party Call
To set up a call from the third-party data terminal, the user selects  from the
entry-level Command Mode menu (see Figure 2-58). The user then enters the characters as
required to call the destination terminal.Calls may be completed as follows.
Note:If a character is entered incorrectly, the ASCII character backspace...