ATT System 25 Reference Manual

User Changeable Options
Administration Requirements
l Data Port:
A data port must be administered to allow the terminal user to change options from
the Command Mode menu.If permission is denied, the user may view the current
option settings but not change them.
l AT&T STARLAN NETWORK Access:
The User Changeable Options feature is not available for ports administered as
STARLAN INTERFACE ports.Refer to the “STARLAN NETWORK Access” feature
description for additional information.
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FEATURES AND SERVICES
Virtual Facilities
Description
A virtual facility (VF) is a call routing facility that is not defined by the physical facility (trunk)
over which calls are routed, but is instead defined by a combination of access codes,
authorization codes, and coded characters that allow special handling of the destination
telephone numbers.VFS can be used to automatically route calls via other carrier networks,
private networks, or tie trunks.
Up to ten virtual facility numbers (VFNs) may be...

Virtual Facilities
If the VF is used in the first position of a routing pattern, calls may queue on it if all of the
routes are busy.
Whenever a VF is used to complete a call (either by dial access or through ARS), call
processing treats the number as a physical facility for Station Message Detail Recording
(SMDR) purposes.Thus, if VF code #190 is used to complete a call, the SMDR call record
will show “#190” as the facility used.
A VFN may contain up to 28 characters. The pound sign (#) is used as an...

FEATURES AND SERVICES
—The “9” is used to access the remote PBX’s ARS.
—The “ V ” represents a pause of 1.5 seconds (allows time for dial tone to
occur).
—The “555 4343” defines the local address of a private network and its
internal routing table.
—   The “ V ” represents a 1.5 second pause.
—The “#5” indicates that the destination number should be inserted here,
rather than at the end of the VF translation.
—   The “ # V ” indicates that the system should transmit a “ V ” symbol as the
first character...

Virtual Facilities
Accessing a Virtual Facility
Dial access is provided by dialing the VF code (#190-#199, including the “#”), followed by
the destination telephone number.
l Example:
— The user dials the following VF code and associated destination telephone
number.
#192 12125551643.
— The stored VFN associated with VF code #192 is defined as
2222 V 333 V 444.
— The first four digits (2222) represent the FAC for a tie trunk group to a remote
PBX.
— The V represents a 1.5 second pause.
— The next three...

FEATURES AND SERVICES
Interactions
When using a VF through dial access, calling restrictions will be based on the station’s class
of service. Dial access VF calls will be completed only if:
l The VF code is valid and not dial restricted.
l The station is not outward restricted.
l The station has dial access permission for the physical facility embedded within the
VFN.
l The destination telephone number is valid and allowed for the station’s toll restriction
class.
VFs cannot be assigned to Facility...

AUDIX Voice Power System
AUDIX Voice Power System
Description
The AT&T AUDIX VOICE POWER (AVP) System provides a group of communications services
that expand System 25 operation in thearea of collecting, processing, and delivering voice
messages for inside users and outside callers. It functions somewhat like a sophisticated system-
wide answering machine and/or an automated attendant. AVP is an adjunct to System 25,
connected by way of special ports on analog tip/ring circuit packs. Administration...

Features and Services
Choosing Passwords
Passwords should be as many digits as possible, and should not be obvious. Avoid those with
ascending digits (e.g., 1234), the same digits (e.g., 0000), digits corresponding to the
employee’s name (e.g., 5646 for John), the current year (e.g., 1993), the same number as
extension (e.g., extension 3455, password 3455), reverse extension (e.g., extension 3455,
password 5543), numbers that identify the user (e.g., social security, employee ID, room
number, etc.)...

FUNCTIONAL DESCRIPTION
Digital Switch 
Common Control
CPU/MEM CP
Switching Network
TDM Bus
Port Circuits
Circuitry Common to All Port CPs
Analog Line (TN742)
ATL Line (ZTN79)
Auxiliary Trunk (TN763)
Data Line (TN726)
DID Trunk (TN753)
Ground Start Trunk (ZTN76)
Loop Start Trunk (ZTN77)
MET Line (TN735)
STARLAN Interface (ZTN84)
Tie Trunk (TN760B)
Tip Ring Line (ZTN78)
System Resources
Service Circuit Clock (ZTN131)
Tone Detector (TN748B)
Pooled Modem (TN758)
DS1 Interface (TN767)
Software
Switched...

Memory
Call Processing
TDM BUS
Port Circuit Packs
Step-By-Step Call Description3-41
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