Telephone keypad

keypad12-key telephone keypaddial padnumeric keypadnumeric keypadsTelephone keypad letter mapping12-key3x4 keypad3×4 numeric keypadalphanumeric keypad
A telephone keypad is the keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number.wikipedia
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Dual-tone multi-frequency signaling

DTMFtouch-tonedual-tone multi-frequency
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 that replaced rotary dialing originally developed in electromechanical switching systems.
The Touch-Tone system using a telephone keypad gradually replaced the use of rotary dial and has become the industry standard for landline and mobile service.

Rotary dial

rotary telephonedialrotary phone
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 that replaced rotary dialing originally developed in electromechanical switching systems.
Touch-tone technology primarily used a keypad in form of a rectangular array of push-buttons for dialing.

Vertical service code

calling featureservice featureCustom Local Area Signaling Services
These keys were added to provide signals for anticipated data entry purposes in business applications, but found use in Custom Calling Services (CLASS) features installed in electronic switching systems.
A vertical service code (VSC) is a sequence of digits and the signals star and number sign dialed on a telephone keypad or rotary dial to enable or disable certain telephony service features.

Keypad

keypadsnumeric keypad
A telephone keypad is the keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number.
On a telephone keypad, the numbers 1 through 9 are arranged from left to right, top to bottom with 0 in a row below 789 and in the center.

Phoneword

mnemonicPhonewordsletters
For example, an interior decorator might license the telephone number 1-800-724-6837, but advertise it as the more memorable phoneword 1-800-PAINTER.
In many countries, the digits on the telephone keypad also have letters assigned.

Numeric keypad

numpadnumber padnumerical keypad
The layout of the digit keys is different from that commonly appearing on calculators and numeric keypads.
It is notably different from the layout of telephone Touch-Tone keypads which have the -- keys on top and -- keys on the third row.

Predictive text

textonymPredictive Text Entrypredict
To compensate for the smaller number of keys, phones used multi-tap and later predictive text processing to speed up the process.
Predictive text is an input technology used where one key or button represents many letters, such as on the numeric keypads of mobile phones and in accessibility technologies.

E.161

ITU E.161ITU-T E.161letters assigned to most of the digits
Letters did not re-appear on phones in Europe until the introduction of mobile phones, and the layout followed the new international standard ITU E.161/ISO 9995-8.
E.161 is an ITU-T Recommendation that defines the assignment of the basic 26 Latin letters (A to Z) to the 12-key telephone keypad.

Text messaging

text messagetextingtext messages
In mobile phones the letters on the keys are used for text entry tasks such as text messaging, entering names in the phone book, and browsing the web.
The small phone keypad and the rapidity of typical text message exchanges has caused a number spelling abbreviations: as in the phrase "txt msg", "u" (an abbreviation for "you"), "HMU"(“hit me up”; i.e., call me), or use of CamelCase, such as in "ThisIsVeryLame".

T9 (predictive text)

T9predictive textpredictive text input
T9 is a predictive text technology for mobile phones (specifically those that contain a 3×4 numeric keypad), originally developed by Tegic Communications, now part of Nuance Communications.

Telephone exchange names

central office nametelephone exchangetelephone exchange name
Originally, they referred to the leading letters of telephone exchange names.

Multi-tap

To compensate for the smaller number of keys, phones used multi-tap and later predictive text processing to speed up the process.
* Telephone keypad letter mapping

Keyboard layout

layoutkeyboard layoutskeyboard
In the course of telephone history, the positions of telephone dials, as well as keypads have been associated with various patterns of mapping letters and characters to numbers (keyboard layout).

Telecommunication

telecommunicationscommunicationstelecom
A telephone keypad is the keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number.

Telephone number

phone numbertelephone numbersphone numbers
A telephone keypad is the keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number.

Bell System

Bell Operating CompanyBell Operating CompaniesBell Telephone
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 that replaced rotary dialing originally developed in electromechanical switching systems.

John Karlin

John E. KarlinJohn Elias Karlin
The development of the modern telephone keypad is attributed to research in the 1950s by Richard Deininger under the directorship of John Karlin at the Human Factors Engineering Department of Bell Labs.

Bell Labs

Bell LaboratoriesBell Telephone LaboratoriesAT&T Bell Laboratories
The development of the modern telephone keypad is attributed to research in the 1950s by Richard Deininger under the directorship of John Karlin at the Human Factors Engineering Department of Bell Labs.

Autovon

Multilevel precedence and preemptionAutomatic Voice Networkmultilevel
For military applications, a fourth, right-most column of keys was added for priority signaling in the Autovon system in the 1960s.

Asterisk

*starasterisks
Initially, between 1963 and 1968, the keypads for civilian subscriber service had keys installed in only ten positions, omitting the lower left and lower right keys that commonly are assigned to the star and number sign signals, respectively.

Electronic switching system

switching systemselectronic switchingdigital exchange telecommunications system
These keys were added to provide signals for anticipated data entry purposes in business applications, but found use in Custom Calling Services (CLASS) features installed in electronic switching systems.

Calculator

pocket calculatorcalculatorselectronic calculator
The layout of the digit keys is different from that commonly appearing on calculators and numeric keypads.

Human factors and ergonomics

ergonomicshuman factorsergonomic
This layout was chosen after extensive human factors testing at Bell Labs.

Number sign

#hash symbolhash
Initially, between 1963 and 1968, the keypads for civilian subscriber service had keys installed in only ten positions, omitting the lower left and lower right keys that commonly are assigned to the star and number sign signals, respectively.

Alpha

ααAlfa
The Greek symbols alpha and omega had been planned originally.