AT&T 2500 series User Manual

Page of 348
2-4
COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW
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The networking software has been packaged to accommodate this type of network evolution.  Table 2-1
shows the types of software (and their PECs) that must be activated to enable particular types of networks.
Table 2-1. Networking Software
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Software
Network Type
_ ____________________________________________________________________
S75/G1 S85/G2
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Package PEC  Package  PEC
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Tandem Tie Trunk 
Basic 
1233-VAS 
Basic 
1252-RS5
ARS 1233-ARS 
(includes 
ARS)
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MS/T 
Uniform Dial Plan 
1233-UDP 
Multipremises 
1252-MP3
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ETN 
Private Network Access 
1233-PNA 
ETN (Standard Network) 
1252-ET3
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DCS DCS 
1233-DCS 
DCS 
1252-DCS
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For ETNs, the ETN (Standard Network) or Private Network Access (PNA) packages need be activated only
on the tandem switches.  (The ETN [Standard Network] or PNA packages can also be activated in main
switches; these are known as intelligent mains.)
SOFTWARE CAPABILITIES
System 75/Generic 1 and
DIMENSION
/System 85/Generic 2 software packages are equivalent in that they
enable the same type of networks; they are different in the they sometimes use different processes to
produce the same result.  Below is an explanation of the networking software, along with System
75/Generic 1 and
DIMENSION
/System 85/Generic 2 software similarities and differences.
Basic Networking Software
The basic software for the
DIMENSION
, System 85, and Generic 2 communication systems contains three
capabilities around which networks are built:
Automatic Route Selection (ARS).  ARS is the feature that provides routing of public network calls.
The feature provides automatic selection from an ordered list of trunk groups and access to the first-
available trunk group in the list. The ordered list of trunk groups is called a routing pattern; the trunk
groups on the list are called preferences.  Up to 254 routing patterns can be established on the System
75 or Generic 1 communications system; on the System 85 or Generic 2, 64 patterns can be made
available.  Each ARS routing pattern has a first-choice preference and one or more alternate preferences
arranged in order of desirability (usually, cheapest to most expensive).  For public network calls, ARS
provides capabilities similar to those provided by Automatic Alternate Routing (AAR) for private