Chapter 1
Using the Cisco Voice Gateway 200
Using a Cisco VG200 Gateway with H.323
1-10
Software Configuration Guide for the Cisco VG200
78-10322-02
FXO Emulation
Figure 1-5
Using FXO Analog Emulation with T1-CAS
To make this work you must obtain Direct Inward Dialing (DID) service from
your local exchange carrier (LEC) on the DS-0 groups used for incoming calls.
DID service is provided only on incoming connections, so to use it, you must
divide your T1 channels into incoming and outgoing DS-0 groups.
You can configure your dial plan on a Cisco VG200 gateway, using Cisco IOS CLI
commands to identify the destination endpoint and coder-decoder (CODEC) for
each incoming call on each DS-0 group. This is a straightforward task, but this
method of configuration does not take full advantage of the Cisco CallManager
and can only be used for H.323 endpoints.
You can configure a Cisco VG200 gateway to direct all incoming calls to the
Cisco CallManager, and configure your dial plan using the Cisco CallManager
Administrator. This simplifies administration and lets you connect simple IP
telephony devices (such as the Cisco IP Phone 7960 and Cisco IP SoftPhone) to
the PSTN. This configuration is described in Chapter 3, “Configuring Voice over
IP.”
Cisco CallManager
H.323 endpoint
Simple IP
telephony devices
Voice Gateway
10/100BaseT Ethernet
33345
PSTN
T1-CAS
DS-0 groups 0-23
FXO emulation
DID incoming lines
DS-0 groups 0-23
Port 0
Port 1
Gateway
