Telephone keypad

keypad12-key telephone keypaddial padnumeric keypads12-key3x4 keypad3x4 numeric keypadalphanumeric keypadnumeric keypadphone 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-tonetouch tone
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

dialrotary telephonerotary 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 featureCLASS
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

keyboardkeypadsnumeric keypad
A telephone keypad is the keypad installed on a push-button telephone or similar telecommunication device for dialing a telephone number.
The invention of the Push-button telephone keypad is attributed to John E. Karlin, an industrial psychologist at Bell Labs in Murray Hill, NJ. 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

mnemoniclettersphone word
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

number padnumpadnumerical 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

Predictive Text Entrytextonympredict
On modern mobile phones and smartphones, the letters on the keys are needed for entering text for text messaging, entering names in the phone book, mobile apps, mobile browser, etc. To compensate for the smaller keys, mobile phones use systems like multi-tap and predictive text processing.
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
On modern mobile phones and smartphones, the letters on the keys are needed for entering text for text messaging, entering names in the phone book, mobile apps, mobile browser, etc. To compensate for the smaller keys, mobile phones use systems like multi-tap and predictive text processing.
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
T9 is a predictive text technology for mobile phones (specifically those that contain a 3x4 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.
Telephone keypad

Multi-tap

On modern mobile phones and smartphones, the letters on the keys are needed for entering text for text messaging, entering names in the phone book, mobile apps, mobile browser, etc. To compensate for the smaller keys, mobile phones use systems like multi-tap and predictive text processing.
* Telephone keypad letter mapping

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

BellBell 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. 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 Telephone LaboratoriesBell 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

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

Asterisk

*asterisksstar
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 switching
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

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

Number sign

#hashhash symbol
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.

Omega

ΩOmega (Ω)ω (omega)
The Greek symbols alpha and omega had been planned originally.