Interacting With The Cisco Aironet Access Point - Cisco 7920 Administration Manual

Interactions with Components in the VoIP Network

Interacting with the Cisco Aironet Access Point

Cisco Wireless IP Phone 7920 Administration Guide for Cisco CallManager Release 3.3 or Later
2-2
Chapter 2 Preparing to Install the Cisco Wireless IP Phone 7920 on Your Wireless Network
The following topics provide an overview of the network components:
Interacting with the Cisco Aironet Access Point, page 2-2
•
Roaming in a Wireless Network, page 2-4
•
• Voice Quality in a Wireless Network, page 2-5
Security Mechanisms in the Wireless Network, page 2-6
•
• Interacting with Cisco CallManager, page 2-8
Interacting with the DHCP Server, page 2-8
•
Wireless voice communication devices use the same access points as wireless data
communication devices, but voice traffic over a WLAN requires different
equipment configurations and layouts than a WLAN that is used exclusively for
data traffic. Data transmission can tolerate a higher level of RF noise, packet
delay, and channel contention than voice transmission can. Delays during data
transmission such as a web page displaying more slowly, do not impact the end
user greatly. But delays during voice transmission can result in choppy or broken
audio making the phone call inaudible.
Wireless voice users are mobile and will roam across a campus or between floors
in a building while connected to a call. On the other hand, data users might move
their PC to another location, but they reconnect at the new location. The ability to
roam is one of the advantages of wireless voice; therefore, RF coverage needs to
include areas not usually covered for data, such as stairwells, elevators, quiet
corners outside conference rooms, and passage ways.
To assure good voice quality and optimal RF signal coverage, you must perform
a site survey that determines thresholds specific to wireless voice. The survey
results provide information for the design and layout of the WLAN for voice. For
more information about the site survey, refer to the Cisco Wireless IP Phone 7920
Deployment Recommendations document.
After deploying and using wireless voice, you should continue to perform post
installation site surveys to verify that the locations of the access points and their
configuration continues to meet the needs of your wireless voice users. When you
add a group of new users or install more equipment or stack large amounts of
inventory, you are changing the wireless environment. You need to verify that the
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