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Chapter 1
Using the Cisco Voice Gateway 200
T1-CAS Analog Port Emulation
T1 is a digital signaling standard that uses time-division multiplexing (TDM) to
divide the available bandwidth of 1.544 Mbps into twenty-four 64-kbps timeslots.
E1 is a similar standard, commonly used in Europe and many parts of Asia, which
provides 2.048 Mbps bandwidth, divided into 32 time slots, with 30 time slots
available for voice conversations.
A DS-0 group is a group or collection of DS-0 timeslots. Each of these DS-0
groups can be used to emulate an FXO analog connection to the PSTN, an FXS
analog connection to a T1 channel bank, or an E&M connection for enabling a
trunk (tie) line.
When you configure your DS-0 groups, you can configure DS-0 hunt groups,
which allow any available voice port to be used for a range of phone numbers.
This eliminates the chance that a single DS-0 could fail, or that a DS-0 is busy at
the time of a call.
To use a Cisco VG200 gateway to interconnect a VoIP network and a T1
connection, you configure from 1 to 24 DS-0 groups for each T1 connection, and
then define a voice port for each DS-0 group. The Cisco VG200 currently supports
T1 connections using channel associated signaling (CAS).
You can use DS-0 groups with FXO analog port emulation to connect to a PSTN
central office (CO). When connecting T1-CAS to the PSTN, either the
Cisco VG200 gateway or the Cisco CallManager must be able to identify the
dialed number (DNIS) of each call and route it to the appropriate endpoint on the
IP network.
78-10322-02
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T1-CAS Analog Port Emulation, page 1-9
FXO Emulation, page 1-10
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FXS Emulation, page 1-11
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E&M Emulation, page 1-11
Linking PBX Users with E&M Trunk Lines, page 1-12
•
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Direct-Inward Dialing on a BRI Port, page 1-13
Using a Cisco VG200 Gateway with H.323
Software Configuration Guide for the Cisco VG200
1-9
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