You can determine the registered or deregistered status of Communications Manager phones for active Communications Manager 4.x clusters and for Communications Manager 4.x clusters on which failover has occurred. Failover occurs when Communications Manager status changes from Primary to Backup.
In this scenario, use the phone deregistration support provided by the 4x_PhoneDeregistrations Knowledge Script. By using this script, you can determine which phones have deregistered and maintain a history of phone deregistrations in the CiscoCM supplemental database.
Communications Managers that fail over contain only a list of phones that have registered since failover occurred; they do not provide a list of phones that deregistered as a result of failover. To determine which phones have deregistered, use the CiscoCallMgr_CCM_PhoneInventory Knowledge Script from the AppManager for Cisco CallManager (CiscoCallMgr) module. This script takes an inventory of phones based on specified search criteria. Make sure to use the Monitor for new/missing phone registrations? parameter to monitor for phone registrations that are new or missing since the last time this script was run.
To determine whether failover has occurred, use the CiscoCallMgr_CCM_RoleStatus or CiscoCallMgr_LossOfHardwarePhones Knowledge Script.