Telephone keypad
Keypad that appears on some telephones
Summary
A telephone keypad is a keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number. It was standardized when the dual-tone multi-frequency signaling (DTMF) system was developed in the Bell System in the United States in the 1960s – this replaced rotary dialing, that had been developed for electromechanical telephone switching systems. Because of the abundance of rotary dial equipment still on use well into the 1990s, many telephone keypads were also designed to be backwards-compatible: as well as producing DTMF pulses, they could optionally be switched to produce loop-disconnect pulses electronically.
Originally created by Robertb-dc
7/22/2003, 5:31:58 PM
Modified
5/19/2026, 3:34:22 AM
Recent revisions
sorted categories alphabetically via [[User:Epicgenius/sortcategories|script]]
Rescuing 9 sources and tagging 0 as dead.) #IABot (v2.0.9.5
Added bibcode. | [[:en:WP:UCB|Use this bot]]. [[:en:WP:DBUG|Report bugs]]. | Suggested by Wikistander | #UCB_toolbar
moved ref to something it covered. copied Danish letter scheme from photos found as "antique Danish dial telephone with letters". updated archived usurped URL.
copyedit
fixed [[MOS:DASH|dashes]] using [[User:Ohconfucius/dashes.js]]
spelling
/* Star key and square key */ find an archive.org copy of the article, read it, include it (I also think this claim is reserved and plausible, now, not probably BS)
redirect bypass from [[International Telecommunications Union]] to [[International Telecommunication Union]] using [[:en:Wikipedia:Tools/Navigation_popups|popups]]
/* Star key and square key */ ITU E.161 just shows a picture of a sextile but calls it a star. <sigh>
/* Star key and square key */ update to reduce [[wp:SYNTH]] and add the patent
using Teardrop-Spoked Asterisk for the star key is less of a good choice than any of the other options on the page. Let's use sextile here for now. Frustratingly, wikipedia search doesn't seem to locate instances of ✻, so it's hard to find other places where this might be misused.
/* Star key and square key */ correct section number for ITU
/* Star key and square key */ add link to the John Koten story (by the way, I'm very dubious of this claim, and will probably call BS on it once I actually read the article)
alpha and omega are the regular names of the symbols, and do not have to be italicized
/* Star key and square key */ not much of a footnote, is it?
/* Star key and square key */Anchor for square key too
/* Star key and square key */ no need to recite the litany of # names when we can just link to that page, I think.
/* Star key and square key (hash key or pound key) */ simplify this section title.
/* Star key and square key (hash key or pound key) */ use english version of source pdf, mention the others
