During the Cold War, the British Telecom speaking clock network was designed to be used in case of nuclear attack to broadcast messages from Strike Command at RAF High Wycombe to HANDEL units at regional police stations. From there, automatic warning sirens could be started and alerts sent to Royal Observer Corps monitoring posts and other civil defence volunteers equipped with manual warning devices. The rationale for using an existing rather than a dedicated system was that it was effectively under test at all times, rather than being activated (and possibly found to be faulty) only in the event of war. The signals to automatic sirens were sent down the wires of individual (unaware) subscribers for the same reason — a customer would report any fault as soon as it occurred, whereas a problem with a dedicated line would not be noticed until it was needed.