lickering light may indicate that a call is on hold. Some telephones have a light next to the button of the extension number that remains lit even when the telephone is not in use. h. The switchhook. This refers to those two little plastic but- tons that press down on a conventional telephone when you hang up the receiver. When you hang up you are actually breaking an electrical circuit that connected you to the per- son at the other end while you were talking. On some telephones, the switchhook may be a single bar that depresses when you hang up. Other telephones have a magnetic switchhook inside the telephone, directly under the receiver when it is hung up, that cannot be seen from the outside. In The Telecom Handbook 30 9 THE TELEPHONE very old movies, we often see someone frantically tapping the switchhook trying to get help as the intruder is banging on the front door. This method was once used to reach an "operator" or switchboard attendant. Instead you would now dial 0. In telephone systems introduced in the 1960's and 1970's, the switchhook was used as a means of activating the system functions such as call transfer. If you held the switchhook down for a second too long, you'd disconnect the call! These functions are now accomplished more easily with feature buttons. Speaker. Most multi-line and a few single-line telephones are equipped with some type of speaker. A speakerphone enables the person using the telephone to have hands-free conversation with another person at a distant location with- out lifting the handset. Some speakers are one way only. This may be called a monitor rather than a speakerphone, which is two-way. The monitor enables the person using the tele- phone to dial out or wait on hold without lifting the handset. They can hear what is on the open line, but cannot speak back to the caller without picking up the handset. Another capability, also called monitoring, enables others in the room to hear both sides of a telephone call in progress, while the person in the room who is speaking us