and other clandestine agents (additional possible uses include communication with embassies when a crisis might dictate destruction of cryptographic equipment and as a backup to normal command systems in wartime). Other intended recipients of secret broadcasts have faster and easier-to-use equipment at their disposal. But number stations are ideal for spies in that they require no special equipment, beyond a short-wave receiver. Morse code skills, once a staple of spy training, are no longer required. Problems with secret broadcast An issue in the past has been the limited bandwidth of the broadcast. Morse code was typically sent at 25 words per minute. Teleprinters could operate at or above 60 words per minute. The military uses a message precedence system to prioritize critical traffic, but all too often, senior commanders insisted on high precedence for lengthy messages lacking real urgency. See also Letter beacon Numbers station Traffic flow security References External links Military radio systems Secure communication Espionage techniques