Phones constantly authenicating to radius server, I would think that WDS would take authenication after phone connects once. Wireless network and phone configured by a contractor. We have a WLSM installed in a 6500, 76 AP installed all on the same subnet?
Any client will reauthenticate when it roams to another AP. The advantage of WDS is that the credentials are cached at the WDS so the authentication doesn't have to go back to the Radius server. Just keep in mind for Fast Secure Roaming to work the WLAN will need to be configured with CCKM and use LEAP or EAP-FAST as the 802.1x type. The 7920 does support FSR. Make sure you have the phone setup for AKM with LEAP and that the SSID they are authenticating to is configured for CCKM and have "authentication network-eap..." configured.