If you administer the time-day-window (TDW) rule, all the associated network regions are disabled regardless of the type of the survivable server. When the TDW day and hour is reached, the system activates the NRs, and all the gateways and telephones in those NRs return to the main server. At the end of the hour, the system checks whether all the gateways have returned. If the gateways have returned to the main server, the system reactivates the feature for the next event. If not, the NRs are disabled, causing all the gateways to register with the survivable server.