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Cisco Wireless IP Phone 7920 Administration Guide for Cisco CallManager Release 4.0 and 4.1
OL-7104-01
Chapter 2 An Overview of the Wireless Network
Components of the VoIP Wireless Network
cause the page to display slowly and might annoy the end user. However, packet
loss during voice transmission can cause choppy or broken audio and make the
phone call inaudible.
Wireless voice users are mobile and can roam across a campus or between floors
in a building while they are connected to a call. Alternately, data users might move
their PC to another location, but they reconnect at the new location. The ability to
roam while maintaining voice session continuity 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 settings suitable to wireless voice. The survey results
provide information for the design and layout of the WLAN for voice; for
example, power levels, channel assignments, and access point placement. For
more information about the site survey, refer to the
Cisco Wireless IP Phone 7920
Design and Deployment Guide
.
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 must verify that the
access point coverage is still adequate for optimal voice communications. See the
“Performing a Site Survey Verification” section on page 6-7
for more
information.
Associating to an Access Point
At startup, the Cisco Wireless IP Phone 7920 uses its radio to scan for access
points with Service Set Identifiers (SSIDs) and encryption types that it
recognizes. The phone builds and maintains a list of eligible access point targets
and uses the following two variables to determine the best access point with which
to associate.
•
Received Signal Strength Indicator (RSSI)—The phone uses this value to
determine the signal strength of available access points within the RF
coverage area. The phone attempts to associate with the access point with the
highest RSSI value.
Содержание 7920 - Unified Wireless IP Phone VoIP
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