Cisco 8821 Manual page 59

AP Groups
AP Groups can be created to specify which WLANs / SSIDs are to be enabled and which interface they should be mapped to as
well as what RF Profile parameters should be used for the access points assigned to the AP Group.
On the WLANs tab, select the desired SSIDs and interfaces to map to then select Add.
Cisco Wireless IP Phone 8821 and 8821-EX Wireless LAN Deployment Guide
59