Specifications

Cisco Unified Wireless IP Phone 7921G Series Deployment Guide 54
802.11 Network Settings
If using 5 GHz, ensure the 802.11a network status is set to enabled.
Set the beacon period to 100ms.
Ensure DTPC Support is enabled.
If using 802.11n capable access points, ensure ClientLink is enabled.
Configure 12 Mbps as the mandatory (basic) rate and 18 – 24 or 54 Mbps as supported (optional) rates.
36-54 Mbps can optionally be disabled, if there are not any applications that can benefit from those rates.
Enable CCX Location Measurement.