|Twenty-seven small frequency bands scattered throughout the entire radio spectrum are allocated to this service internationally. Some 1,300 digital, analog, pulse, and spread-spectrum emission types may be transmitted. Millions of amateur operators in all areas of the world communicate with each other directly or through various relay (repeater) systems and amateur-satellites that are established by the amateur community. They exchange messages by voice, teleprinting, telegraphy (Morse code), facsimile, and television.All frequencies are shared. No frequency is assigned for the exclusive use of any amateur station.� Station control operators must cooperate in selecting transmitting channels to make the most effective use of the frequencies.