We have migrated from a Autonomous Wireless Solution (1200 AP) to Centralized Wireless LAN Controller (WLC 5500). The WLANs work fine, but the call on the Wireless Phone 7921, are experiencing problems, sound in one way, drop of calls, problems no present previously with the autonoums solution. The QoS of the Voice WLAN is set to Voice, but the problems persist. Any Suggestion ??