Specifications

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Cisco 1751 Router Software Configuration Guide
OL-1070-01
Configure Number Expansion
In most corporate environments, the telephone network is configured so that you can reach a destination
by dialing only a portion (an extension number) of the full E.164 telephone number. VoIP can be
configured to recognize extension numbers and expand them into their full E.164 dialed number by
using two commands in tandem: destination-pattern and num-exp. Before you configure these two
commands, it helps to map individual telephone extensions with their full E.164 dialed numbers. This
can be done easily by creating a number expansion table.
Create a Number Expansion Table
In Figure 2, a small company decides to use VoIP to integrate its telephony network with its existing IP
network. The destination pattern (or expanded telephone number) associated with Cisco 1751 Router 1
(left of the IP cloud) is (408) 555-xxxx, where xxxx identifies the individual dial peers by extension.
The destination pattern (or expanded telephone number) associated with Cisco 1751 Router 2 (right of
the IP cloud) is (729) 555-xxxx.
Figure 2 Sample VoIP Network
Table 1 shows the number expansion table for this scenario.
408 555-1002
408 555-1001
408 555-1003
729 555-3002 729 555-2002
729 555-3001 729 555-2001
Cisco 1751
Router 1
WAN WAN
10.1.1.1
10.1.1.2
Cisco 1751
Router 2
Voice port
0/0
51078
Voice port
1/0
Voice
port
0/1
Voice port 1/0
Voice port 1/1
Voice port 0/1
Voice port 0/0
IP cloud