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Cisco 1751 Voice-over-IP Quick Start Guide
78-11259-05
Configuring Voice-over-IP
Figure 18
FXO Gateway to PSTN
To create a POTS dial peer for an FXS interface as explained earlier, you enter the complete telephone
number of the attached telephone as the destination pattern for incoming calls. However, to create a
POTS dial peer for an FXO interface, the destination pattern refers to outgoing calls, and you can include
wildcards in it because the PSTN performs the switching.
The VoIP feature can also remove digits that you do not want to send to the PSTN. For instance, to dial
9 to reach an outside line (that is, the analog PSTN), enter the following commands:
West>
enable
Password:
West#
configure terminal
West(config)#
dial-peer voice 201 pots
West(config-dial-peer)#
destination-pattern 9
West(config-dial-peer)#
port 0/0
When you dial 9, the router makes a connection to the PSTN through voice port 0/0. The PSTN then
provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.
To enable
East
router users to make calls over the
West
router local PSTN, enter the following
commands:
East(config)#
dial-peer voice 701 voip
East(config-dial-peer)#
destination-pattern 7
East(config-dial-peer)#
session target ipv4:192.168.19.27
West(config)#
dial-peer voice 601 pots
West(config-dial-peer)#
destination-pattern 7
West(config-dial-peer)#
port 0/0
When you dial 7 on the
East
router, the call is connected to the PSTN on the
West
router. The PSTN then
provides a dial tone, and any digits you enter on the telephone thereafter are interpreted on the PSTN.
Note
In this example,
West
router voice port 0/0 has two separate POTS dial peers associated with it. Dial peer
201 matches calls beginning with the digit 9 and handles PSTN calls originating from the
West
router.
Dial peer 601 matches calls beginning with the digit 7 and handles calls to the PSTN originating from
the
East
router.
West
IP cloud
PSTN
cloud
51077
FXO VIC
1/0
FXS VIC
0/0
Source
Destination
dial-peer voice 201 pots
destination-pattern 9
port 0/0
