Configuring Voice over IP
VoIP Basics
92
Cisco VGD 1T3 Voice Gateway Software Configuration Guide
This chapter briefly introduces the subject of configuring VoIP and describes the first few configuration
tasks. It describes, at a high level, some of the voice QoS features that you can enable. Most important,
it points you to other references from which you can gain a broader and deeper look at the subject.
This chapter describes the following topics:
•
VoIP Basics, page 92
•
Configuring Basic VoIP, page 96
•
Voice QoS Basics, page 102
•
Enabling QoS Features for VoIP, page 103
•
Additional Resources, page 108
Tip
It is critical that you consult the additional references cited throughout and at the end of the chapter
before you configure VoIP. These plus additional references throughout the Cisco website (search for
configure voip to locate the most current references) provide the information that you need to optimize
settings. The more information that you have at your disposal, the greater your probability of success,
as measured by cost savings and user acceptance.
Note
Although VoIP technology is primarily software-based, it requires that you install a universal port or
voice feature card into the appropriate slot of your Cisco VGD 1T3 voice gateway. The number of ports
or channels available for sending VoIP data depends on the capacity of your card.
VoIP Basics
Before you configure VoIP on your gateway, it might help to understand at a high level what happens
when you place a VoIP call. Think of each event in a call flow as occurring on one of the several “legs”
of a call, as shown in the following typical scenario. (See
Figure 1
.) Other scenarios are possible, of
course, including ones where the call destination is an IP phone and the call never leaves the IP network.
•
Call-leg 1: Originating device to originating gateway
•
Call-leg 2: Originating gateway into the IP network
•
Call-leg 3: IP network to destination gateway
•
Call-leg 4: Destination gateway to destination device
Figure 1
Call Legs
Source
Destination
Call leg 1
(POTS dial peer)
Call leg 2
(VoIP dial peer)
Call leg 3
(VoIP dial peer)
Call leg 4
(POTS dial peer)
35950
IP network
V
V
