Push-button telephone

The push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to having a rotary dial as in earlier telephone instruments. Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field-tested in a No. 5 Crossbar switching system in Pennsylvania.Bell Telephone Laboratories, A History of Engineering and Science in the Bell System – Switching Technologies (1975, AT&T) The technology at that time proved unreliable and it was not until after the invention of the transistor that push-button technology became practical. On 18 November 1963, after approximately three years of customer testing, the Bell System in the United States officially introduced dual-tone multi-frequency (DTMF) technology under its registered trademark Touch-Tone. Over the next few decades touch-tone service replaced traditional pulse dialing technology and it eventually became a world-wide standard for telecommunication signaling. Although DTMF was the driving technology implemented in push-button telephones, some telephone manufacturers used push-button keypads to generate pulse dial signaling. Before the introduction of touch-tone telephone sets, the Bell System sometimes used the term push-button telephone to refer to key system telephones, which were rotary dial telephones that also had a set of push-buttons to select one of multiple telephone circuits, or to activate other features. Digital push-button telephones were introduced with the adoption of metal–oxide–semiconductor (MOS) integrated circuit (IC) technology in the early 1970s, with features such as the storage of phone numbers (like in a telephone directory) on MOS memory chips for speed dialing. The concept of push buttons in telephony originated around 1887 with a device called the micro-telephone push-button, but it was not an automatic dialing system as understood later.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts (17)

Related lectures (2)

Telephone keypad

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 that replaced rotary dialing originally developed in electromechanical switching systems. Because of the installed abundance of rotary dial equipment well into the 1990s, many telephone keypads were also designed to produce loop-disconnect pulses electronically, and some could be optionally switched to produce either DTMF or pulses.

History of the telephone

This history of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent was granted to Alexander Graham Bell in 1876. Before the invention of electromagnetic telephones, mechanical acoustic devices existed for transmitting speech and music over a greater distance. This distance was greater than that of normal direct speech. The earliest mechanical telephones were based on sound transmission through pipes or other physical media.

Telephone exchange

A telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital systems to establish telephone calls between subscribers. In historical perspective, telecommunication terms have been used with different semantics over time. The term telephone exchange is often used synonymously with central office, a Bell System term.

The short-time Fourier transform MOOC: Digital Signal Processing I

Explores the short-time Fourier transform for analyzing signals in time-frequency domains.

Electrical Installations: Basics and Graphic Symbols

Covers the basics of electrical installations, including emergency lighting, switches, outlets, safety devices, and graphic symbols.