Chapter 9 Troubleshooting the Cisco Wireless IP Phone 7920
Resolving Voice Quality and Roaming Problems
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Cisco Wireless IP Phone 7920 Administration Guide for Cisco CallManager Release 4.0 and 4.1
OL-7104-01
Voice Quality Deteriorates While Roaming
Check the RSSI on the destination access point to see if the signal strength is
adequate. The next access point should have an RSSI value of 35 or greater.
Check the site survey to determine if the channel overlap is adequate for the phone
and the access point to hand off the call to the next access point before the signal
is lost from the previous access point.
Check to see if noise or interference in the coverage area is too great.
Check that signal to noise ratio (SNR) levels are 25 db or higher for acceptable
voice quality.
Delays in Voice Conversation While Roaming
Use the Site Survey Utility on the Cisco Wireless IP Phone 7920 to see if there is
another acceptable access point as a roaming option. The next access point should
have an RSSI value of 35 or greater to roam successfully.
Check the Cisco Catalyst 45xx switch to see if it has the correct version of
Supervisor (SUP) blades. The blades must be versions SUP2+ or higher to prevent
roaming delays.
Phone Loses Connection with Cisco CallManager While Roaming
Check that the RF signal strength is good. Use the Site Survey Tool and check the
RSSI value for the next access point.
Check that the next access point has connectivity to Cisco CallManager.
Check that the next access point has the same authentication type as the phone.
There might be a mismatch.
Check that the access point is in the same subnet as the previous access point. The
Cisco Wireless IP Phone 7920 is capable of Layer 2 roaming only.
Layer 3 roaming requires WLSM that uses GRE
If using LEAP authentication, check that the access point is not using filters to
block TCP ports. The ACS server uses port 1645 for authentication and 1646 for
accounting and the RADIUS server uses port 1812 for authentication and 1813 for
accounting.
Содержание 7920 - Unified Wireless IP Phone VoIP
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