Specifications

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Catalyst 4224 Access Gateway Switch Software Configuration Guide
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Chapter 6 Configuring VoIP
Configure Dial Peers
Configure Number Expansion
To define how to expand an extension number into a particular destination
pattern, use the following global configuration command:
num-exp extension-number extension-string
extension-number represents the digit(s) defining an extension number to be
expanded, whereas extension-string represents the digit(s) defining an extension
string to be expanded.
Use the show num-exp command to verify that you have mapped the telephone
numbers correctly.
After you have configured dial peers and assigned destination patterns to them,
use the show dialplan number command to see how a telephone number maps to
a dial peer.
Configure Dial Peers
The key to understanding how VoIP functions is to understand dial peers. All of
the voice technologies use dial peers to define the characteristics associated with
a call leg. Dial peers are used to apply specific attributes to call legs and to
identify call origin and destination.
As shown in Figure 6-3 and Figure 6-4, a call leg is a discrete segment of a call
connection that lies between two points in the connection. Each call leg
corresponds to a dial peer. An end-to-end call consists of four call legs, two from
the perspective of the source Catalyst 4224 (Figure 6-3) and two from the
perspective of the destination Catalyst 4224 (Figure 6-4). Attributes applied to a
call leg include QoS, Coder-Decoder (codec), voice activity detection (VAD), and
fax rate.