Telephone keypad
A telephone keypad is a
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.[2][3] The modern keypad is laid out in a rectangular array of twelve push buttons arranged as four rows and three columns of keys. For military applications, a fourth, right-most column of keys was added for priority signaling in the Autovon system in the 1960s. Initially, between 1963 and 1968, the keypads for civilian subscriber service omitting the lower left and lower right keys that commonly are assigned to the star (✻) and number sign (#) signals, respectively. 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.[4]
Layout
The layout of the digit keys is different from that commonly appearing on
The key labeled ✻ was officially named the "star" key. The key labeled # is officially called the "
These can be used for special functions. For example, in the UK, users can order a 7:30 am alarm call from a BT telephone exchange by dialing: ✻55✻0730#.[8]
Most of the keys also bear letters according to the following system:
Number | Letter |
---|---|
0 | none (on some telephones, "OPERATOR" or "OPER") |
1 | none (on some older telephones, QZ) |
2 | ABC |
3 | DEF |
4 | GHI |
5 | JKL |
6 | MNO (on some older telephones, MN) |
7 | PQRS (on older telephones, PRS) |
8 | TUV |
9 | WXYZ (on older telephones, WXY) |
These letters have been used for multiple purposes. Originally, they referred to the leading letters of
The letters have also been used, mainly in the United States, as a technique for remembering telephone numbers easily. 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. Sometimes businesses advertise a number with a mnemonic word having more letters than there are digits in the phone number. Usually, this means that the caller just stops dialing at seven digits after the area code or that the extra digits are ignored by the central office.
In
Key tones
Pressing a single key of a traditional analog telephone keypad produces a telephony signaling event to the remote switching system. For touchtone service, the signal is a
1209 Hz | 1336 Hz | 1477 Hz | 1633 Hz | |
---|---|---|---|---|
697 Hz | 1 | 2 | 3 | A |
770 Hz | 4 | 5 | 6 | B |
852 Hz | 7 | 8 | 9 | C |
941 Hz | ✻ | 0 | # | D |
Letter mapping
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).
The system used in Denmark[failed verification] was different from that used in the U.K., which was different from the U.S. and Australia.[9] The use of alphanumeric codes for exchanges was abandoned in Europe when international direct dialing was introduced in the 1960s, because, for example, dialing VIC 8900 on a Danish telephone would result in a different number to dialling it on a British telephone. At the same time letters were no longer placed on the dials of new telephones.
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. The ITU established an international standard (ITU E.161) in the mid-1990s, and that should be the layout used for any new devices.[10] There is a standard, ETSI ES 202 130, that covers European languages and other languages used in Europe, published by the independent ETSI organisation in 2003[11] and updated in 2007.[12] Work describing some principles of the standard is available.[13]
Since many newer smartphones, such as the Palm Treo and BlackBerry, have full alphanumeric keyboards instead of the traditional telephone keypads, the user must execute additional steps to dial a number containing convenience letters. On certain BlackBerry devices, a user can press the Alt key, followed by the desired letter, and the device will generate the appropriate DTMF tone.[14]
See also
References
- ^ Agogino, Alice (November 18, 2009). "Engineering Education "Today in History" Blog: Bell Telephone introduces push button telephone". Engineering Pathway. Archived from the original on January 27, 2013.
- ^ B.L. Hanson, A Brief History of Applied Behavioral Science at Bell Laboratories, Bell System Technical Journal 62(6) 1571–1590 (July–August 1983), p.1578
- ^ .
- ^ D.P. Worrall, New Custom Calling Services, Bell System Technical Journal 61(5) 821–839 (May–June 1982)
- ^ doi:10.1037/h0048722.
- ^ Brady Haran (producer), Sarah Wiseman (interviewee) (2013-08-29). Phone Numbers - Numberphile. Archived from the original on 2021-12-12. Retrieved 2016-05-11.
- ^ Koten, John F., " *# ", WSJ.Money Magazine, Issue 5, p. 22 (Spring 2014). The star and number sign were likely first suggested by John A. "Jack" Koten (1929-2014), a corporate communications specialist with Bell Labs in Chicago, reasoning that the new keys would be easier to explain to a public already familiar with typewriter symbols.
- ^ "Reminder Call Instructions | BT Business".
- ^ Phone Key Pads Archived 2015-03-15 at the Wayback Machine
- ^ E.161 : Arrangement of digits, letters and symbols on telephones and other devices that can be used for gaining access to a telephone network
- ^ ETSI (2003-10-29), ETSI ES 202 130 Ver. 1.1.1: Human Factors (HF); User Interfaces; Character repertoires, ordering rules and assignments to the 12-key telephone keypad, ETSI, retrieved 2011-11-03
- ^ ETSI (2007-09-06), ETSI ES 202 130 Ver. 2.1.2: Human Factors (HF); User Interfaces; Character repertoires, orderings and assignments to the 12-key telephone keypad (for European languages and other languages used in Europe), ETSI
- S2CID 20736144
- ^ Blackberry Tips, PC World, October 2005.