Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Rotary dial
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
{{short description|Device for sending telephone numbers}} {{refimprove|date=February 2015}} [[File:Rotarydial.JPG|right|thumb|A traditional North American rotary telephone dial]] A '''rotary dial''' is a component of a [[telephone]] or a [[telephone switchboard]] that implements a [[Signaling (telecommunications)|signaling]] technology in [[telecommunications]] known as [[pulse dialing]]. It is used when initiating a [[telephone call]] to transmit the destination telephone number to a [[telephone exchange]] as a succession of individual digits. On the rotary dial, the digits are arranged in a circular layout, with one finger hole in the finger wheel for each digit. For dialing a digit, the wheel is rotated against spring tension with one finger positioned in the corresponding hole, pulling the wheel with the finger to a stop position given by a mechanical barrier, the finger stop. When released at the finger stop, the wheel returns to its home position driven by the spring at a speed regulated by a [[governor device]]. During this return rotation, an electrical switch interrupts the direct current (DC) of the telephone line ([[local loop]]) the specific number of times associated with each digit and thereby generates electrical [[pulse (signal processing)|pulses]] which the telephone exchange decodes into each dialed digit. Thus, each of the ten digits is encoded in sequences to correspond to the number of pulses; thus, the method is sometimes called ''decadic dialing''. Pulse count dialing is a digital addressing system which uses decimal pulse count modulation. The typical average baud rate is 10 bits per second, though the system will usually accept from about 9 through 13 pulses per second, a requirement due to variations in the rotary dial mechanism governor speed. The first patent for an automatic telephone exchange was granted to [[Almon Brown Strowger]] on November 29, 1892, but the commonly known rotary dial with holes in the finger wheel was not introduced until about 1907. While used in telephone systems of the independent telephone companies, rotary dial service in the [[Bell System]] in the United States was not common until the early 1920s.<ref>{{cite web|last1=Roberts|first1=William Lee|title=A look at the evolution of the Dial Telephone|url=http://www.arctos.com/dial/|access-date=15 January 2016}}</ref> From the 1960s onward, the rotary dial was gradually supplanted by [[push-button telephone|push-button telephones]], first introduced to the public at the [[1962 World's Fair]] under the trade name [[Touch-Tone]] (DTMF). Touch-tone technology primarily used a [[telephone keypad|keypad]] in the form of a rectangular array of push-buttons. Although no longer in common use, the rotary dial's legacy remains in the verb "to dial (a telephone number)".
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)