The manipulation of a telephone instrument is quite simple. In nearly every type of instrument the receivers are hung on a hook which is pivoted on an axis. This movable hook has a spring attached to it so that, when the receiver is hung on it, the hook falls and distends the spring. If the receiver is unhooked the spring is released and the hook is drawn up. It is really a switch, and the up-and-down movement causes the proper connections of line and bell, and line and telephone to be made. To enter into communication with another person through the exchange, the handle of the magneto-generator is turned, or a button is pressed. The exchange answer the signal by ringing the subscriber's bell. The receiver is then unhooked and placed to the ear, and the mouth is placed opposite the microphone. The attendant at the exchange asks what number is required, which being given the proper connection is made there, and the two persons are now in direct communication. When the conversation is finished , the bell is again rung to signify the fact, and the attendant at the exchange disconnects them.