Cisco PA-VXA Series, Руководство по установке и настройке

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T1/E1 Digital Voice Port Adapter Installation and Configuration
OL-3592-02
Chapter 4 Configuring the PA-VXA, PA-VXB, and PA-VXC
Configuring Voice over IP
Expand a Number
To define how to expand an extension number into a particular destination pattern, use the following
command in global configuration mode:
num-exp extension-number extension-string
You can verify the number expansion information by using 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, you can verify number
expansion information by using the show dialplan number command to see how a telephone number
maps to a dial peer.
Configure Dial Peers
The key point to understanding how VoIP functions is to understand dial peers. Each dial peer defines
the characteristics associated with a call leg, as shown in
Figure 4-3 and Figure 4-4 . A call leg is a
discrete segment of a call connection that lies between two points in the connection. All of the call legs
for a particular connection have the same connection ID.
There are two different kinds of dial peers:
• POTS—Dial peer describing the characteristics of a traditional telephony network connection.
POTS peers point to a particular voice port on a voice network device.
•
VoIP—Dial peer describing the characteristics of a packet network connection; in the case of VoIP,
this is an IP network. VoIP peers point to specific VoIP devices.
An end-to-end call comprises four call legs, two from the perspective of the source router as shown in
Figure 4-3 , and two from the perspective of the destination router as shown in Figure 4-4 . A dial peer is
associated with each one of these call legs. Dial peers are used to apply attributes to call legs and to
identify call origin and destination. Attributes applied to a call leg include QoS, codec, VAD, and fax
rate.
Figure 4-3 Dial Peer Call Legs from the Perspective of the Source Router
10353
IP cloud
Destination
Source
Call leg for POTS
dial peer 1
Source router
Call leg for VoIP
dial peer 2