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 administered. Each stored number may be
up to 28 characters in length and is associated with a code in the range of #190 to #199.
The first digits in a stored VFN must be the facility access code (FAC) for a physical trunk
group over which the call is to be routed.A series of digits and special characters are
stored following the FAC to define additional routes,Inter-Exchange Carrier (lXC) codes,
identification codes, or instructions concerning special handling of the destination telephone
number. When a VF has been defined using a particular trunk group, it has full access to all
trunks in that group. It is considered“busy” only when the physical trunk group is busy.
When a VF is dial accessed by a system user, calling restriction is based on the station’s
administered calling restrictions.
A system user may gain access to a VF by:
l Dialing the VF code (#190-#199).
l Storing the VF code as the first digits on a REP DIAL button. Other digits (for
example, the destination telephone number) may be stored following the VF code.
l Dialing a System Speed Dialing code (#100-#189) that contains a VF as part of the
stored number. The VF code must be the first digits stored in the Speed Dialing
number.
l Dialing a Personal Speed Dialing code (#20-#39) that contains a VF as part of the
stored number. The VF code must be the first digits stored in the Speed Dialing
number.
l Using Automatic Route Selection (ARS) and having a VF as the route selected by
ARS.
Note:The system can be administered to allow or restrict dial access for each VF
code. If dial access is restricted (system default), a VF may be accessed only
when used in an ARS routing pattern.
When virtual facilities are used in ARS patterns, they assume the same capabilities and
restrictions as physical facilities. For example:
l Each VF may have a digit deletion and insertion scheme associated with it.
l Selective restriction of a VF may be accomplished by assignment of Facility
Restriction Levels (FRLs).
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							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 escape character
within the digit string and indicates that the character following the pound sign requires
special interpretation.The following table defines the special characters that may be
included in a VFN.
CHARACTERFUNCTION
V1.5 second pause
# VTransmit V
# #Transmit #
# 5Insert dialed digits (destination telephone
number) here. The destination telephone
number may be up to 16 digits in length
(21 if ARS digit translations have
occurred).
If #5 is used, it must be placed within the
last nine digits of the VFN. If #5 is not
used within a VFN, the dialed digits are
appended to the end of the VFN.
# 8Begin transmission of End-to-End
Signaling (system begins transmitting
touch-tone signals to the far end switch).
Examples of Virtual Facility Numbers
The use of VFS can be demonstrated with the following examples:
l Example 1: VF Code = #191, VFN = 100 10288
—
The first three digits (100) represent the FAC for a CO trunk group.
—
10288 represents an access code for a non-primary IXC.
—
The destination telephone number (dialed by the user) will be transmitted
after this IXC access code, since “#5” was not used within the VF number.
l Example 2:VF Code = #193, VFN = 221 9 V 555 4343 V # 5 # V 12345
lThe first three digits (221) represent the FAC for a tie trunk to a remote PBX.
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							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 of an identification code.
—The “12345” represents the remaining characters in the identification code.
l Example 3:VF Code = #195, VFN = 104 5554567 VVVV 1234 V 9
This example demonstrates how a VF might be used in place of a tie trunk group
connecting two local PBXs, when you have permission to access the other PBX’sS
facilities to complete calls.
—The first three digits (104) represent the FAC for a CO trunk group.
—
The “5554567” represents the number for the other PBX.
—   The “ VVVV ”represents a 6 second pause (allows time for the other PBX
to answer and return new dial tone).
—  The “1234” represents a“barrier” (security) code required to access the
other PBX’s facilities.
—The V represents a 1.5 second pause.
—
The “9” represents an ARS access code for the other PBX.
—Since “#5” was not used within the VFN, the destination telephone number
(dialed digits) will be transmitted after this ARS access code.
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							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 digits (333) represent the security code required by the remote
PBX, indicating that you have permission to access their facilities.
— The V represents a 1.5 second pause, as the remote PBX checks the validity
of your security code.
— The final three digits (444) represent the FAC required by the remote PBX to
access their Band 5 WATS trunks.
— Since “#5” was not embedded within this VFN, the destination telephone
number (12125551643) will be transmitted after the WATS access code.
VF codes may be included in numbers stored in REP DIAL buttons, System Speed Dialing
codes, and Personal Speed Dialing codes if the VF code is used at the beginning of these
numbers. VF codes may not be assigned to FACILITY buttons and may not be embedded in
other virtual facility numbers.
VFs may be used in ARS routing patterns just as if they were physical facilities.
Considerations
VFs enhance the Automatic Route Selection feature by increasing the number of facility types
available for use in routing patterns.Using ARS ensures that the least-cost facility is used to
complete each call. User intervention is minimized and associated user dialing errors are
essentially eliminated.
In addition, in those systems where users are permitted dial access to VFs, user dialing of
long digit strings is minimized, as are the associated dialing errors.
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							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 buttons.Button access is provided by programming REP
DIAL buttons only.
Administration Requirements
A VF must be programmed via System 25 administration. The following items are
administrable:
l Specify a Virtual Facility code (#190-#199).
l Assign a Virtual Facility number to this code.
l Allow dial access to this Virtual Facility (yes or no).
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							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 procedures
establish the proper System 25-to-AVP interface and set up the desired AVP capabilities.
The AVP hardware and software are part of System 25’s Integrated Solution.
Five separate services are available with AVP. The first listed is user-oriented, that is, intended
primarily for people inside the system. The other four are caller-oriented, that is, designed for
managing incoming calls.
l
l
l
l
lVoice Mail Service—The primary service of AVP. It allows users to send voice messages to
each other, retrieve their own messages (both inside and outside), record personal
greetings to callers, and administer passwords.
Automated Attendant Service—Answers incoming calls and gives the caller a choice of
destinations (including attendant) or of recording a message for some inside station.
Announcement Service—Provides simple announcements to callers, then disconnects.
Useful for answering calls during nonbusiness hours and for providing information to
employees.
Call Coverage Service—Answers incoming calls and allows the caller to record a message
or be transferred to an attendant.
Message Drop Service—Allows certain users to record messages to solicit information from
callers. After dialing an assigned number and hearing the message, callers can record their
responses. Useful for product and marketing surveys.
For complete information on AVP, refer to its own set of documentation.
Security Considerations
Potential Abuse of the Feature
Unauthorized persons concentrate their activities in two areas with AUDIX Voice Power: (1) they try
to locate unused or unprotected mailboxes and use them as drop-off points for their own messages,
or (2) they try to transfer out of AUDIX Voice Power, gain access to an outgoing trunk, and make
long distance calls.
Techniques for Minimizing Abuse
1. Requires employees who have voice mailboxes to use passwords to protect their mailboxes.
Follow secure password procedures as described below:
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							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.)
Establishing a Policy
As a safeguard against toll fraud, change passwords frequently. Set password expiration times
and tell users when the changes go into effect. Changing passwords routinely on a specific
date (such as the first of the month), helps users to remember to do so.
2. The AUDIX Voice Power administrator should remove unneeded voice mailboxes from the
system immediately.
3. Set up AUDIX Voice Power to limit transfers to subscribers only.
4. Program the System 25 to:
l Block direct access to outgoing lines and force the use of account codes.
l Disallow trunk-to-trunk transfer unless it is required.
l Assign toll restriction levels to AUDIX Voice Power ports.
l If you do not need to use the Outcalling feature of AUDIX Voice Power, completely
restrict the outward calling capability of the AUDIX Voice Power ports.
5. Monitor SMDR reports and/or Call Accounting System reports for outgoing calls that might be
originated by AUDIX Voice Power ports.
Interactions
The following features interact with AVP.
Leave Word Calling: AVP also supports the System 25 feature, Leave Word Calling (LWC), which
is covered in a separate feature description in Section 2, “Features and Services.”
Night Service, Directed: AVP ports maybe assigned Directed Night Service responsibilities.
Hardware Requirements
An AUDIX Voice Power System must be connected to the System 25 by way of a port on a ZTN78
Tip Ring Line circuit pack.
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							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 Services Software
Administrative Software
Maintenance Software
Memory Allocation
Real-Time Constraints
Software Partitioning
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3-2
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3-6
3-9
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3-25
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							Memory
Call Processing
TDM BUS
Port Circuit Packs
Step-By-Step Call Description3-41
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