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CXtec Knowledge BaseStructured Cabling Telephony |
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RotaryA rotary dial is a small piece of equipment attached to a telephone or switchboard that transmits a series of electrical pulses. Referred to as pulse dialing, each pulse corresponds to the number dialed. The original version of the rotary dial featured lugs where the holes would be on modern rotary dials. This early model was patented in 1898 by the Almon Strowger company. The rotary phone with holes in the dial did not appear until 1904 and was not used until Bell introduced it in 1919. When touch tone dialing was incorporated into phones in the 1970s, rotary phones began to be phased out; touch tone uses a number keypad as opposed to a dial. Currently, some telephone service providers are not designed to support rotary dialing. However, you may be able to pay an additional fee to activate rotary dialing as part of your monthly package. Keypads, or dial pads, found on touch tone phones of today typically contain 12 keys that are numbered from 0 to 9 and marked with "*" and "#." Although the setup is different, the touch tone phone sends identical signals to those of a rotary phone. How it works In telephony, dialing is the act of placing a call. To dial a number on a rotary phone, a person puts one of their digits into the finger hole of the corresponding number they wish to enter. Then, the user turns the dial clockwise until their finger touches the finger stop. Now, the user can release their finger, and a spring will return the dial to its normal state. For instance, if the person dials "4," as the dial returns to the resting position, electrical contacts located beneath the dial will open and close four times. As a result, four pulses would be sent to the call center, and the switchboard would recognize that the number four was dialed. |
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