 For Central office staff this could be a scary time as seconds and then perhaps minutes passed while they knew subscribers who picked up their phones would get dead silence until the phase was over and the processor regained "sanity" and resumed connecting calls.Greater phases took longer, clearing all call registers, thus disconnecting all calls and treating any off-hook line as a request for dial tone.If the automated phases failed to restore system sanity, there were manual procedures to identify and isolate bad hardware or buses.