Acoustic coupler

acousticACacoustic couplingacoustic data couplersacoustic modemsacoustically coupledacoustically coupled modemcouplertelephone coupler
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.wikipedia
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Coupling (electronics)

couplingcouplecoupled
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.
* Acoustic coupler

Carterfone

Carterfone decisionCarterphoneCarterphone decision
A second court decision in 1968 regarding the Carterfone further allowed any device not harmful to the system to be connected directly to the AT&T network.
The device was acoustically, but not electrically, connected to the public switched telephone network.

Modem

modemsdial-up modem56k modem
This decision enabled the proliferation of later innovations like answering machines, fax machines, and modems.
Since most handsets were supplied by Western Electric and thus of a standard design, acoustic couplers were relatively easy to build.

Robert Weitbrecht

Robert Weitbrecht created a workaround for the Bell restrictions in 1963.
Robert Haig Weitbrecht was an engineer at SRI International and later the spin-off company Weitbrecht Communications who invented a type of a modem (a form of acoustic coupler).

Fax

fax machinefacsimilefax machines
This decision enabled the proliferation of later innovations like answering machines, fax machines, and modems.
This audio tone was then transmitted using an acoustic coupler (a speaker, in this case) attached to the microphone of a common telephone handset.

Bulletin board system

BBSbulletin board systemsBBSes
Such devices facilitated the creation of dial-up bulletin board systems, a forerunner of modern internet chat rooms, message boards, and e-mail.
Early modems were generally very simple devices using acoustic couplers to handle telephone operation.

John van Geen

Such modems or couplers were developed around 1966 by John van Geen at the Stanford Research Institute (now SRI International), that mimicked handset operations.
John van Geen (August 17, 1929 – June 6, 2000) was a researcher at the Stanford Research Institute (now SRI International) who was known for his advances in the acoustically coupled modem.

Telecommunications device for the deaf

TDDTTYtelecommunications devices for the deaf
Many models of TDDs (Telecommunications Device for the Deaf) still have a built-in acoustic coupler, which allow more universal use with pay phones and for 911 calls by deaf people.
In 1964, Marsters, Weitbrecht and Andrew Saks, an electrical engineer and grandson of the founder of the Saks Fifth Avenue department store chain, founded APCOM (Applied Communications Corp.), located in the San Francisco Bay area, to develop the acoustic coupler, or modem; their first product was named the PhoneType.

Telecommunication

telecommunicationscommunicationstelecom
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.

Network interface device

optical network terminalinterfacenetwork interface
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.

Telephone

phonetelephonesLocal Telephone Service
In telecommunications, an acoustic coupler is an interface device for coupling electrical signals by acoustical means—usually into and out of a telephone.

Electrical connector

connectorconnectorselectrical connection
The link is achieved through converting electric signals from the phone line to sound and reconvert sound to electric signals needed for the end terminal, such as a teletypewriter, and back, rather than through direct electrical connection.

Breakup of the Bell System

Bell System divestiturebreakup of AT&TAT&T divestiture
Prior to its breakup in 1984, Bell System's legal monopoly over telephony in the United States allowed the company to impose strict rules on how consumers could access their network.

Bell System

Bell Operating CompanyBell Operating CompaniesBell Telephone
Prior to its breakup in 1984, Bell System's legal monopoly over telephony in the United States allowed the company to impose strict rules on how consumers could access their network.

Telephony

digital telephonytelephonedigital
Prior to its breakup in 1984, Bell System's legal monopoly over telephony in the United States allowed the company to impose strict rules on how consumers could access their network.

Registered jack

RJ11RJ-11RJ45
In many households, telephones were hard-wired to wall terminals before connectors like RJ11 and BS 6312 became standardized.

British telephone socket

BS 6312British telephone sockets431A
In many households, telephones were hard-wired to wall terminals before connectors like RJ11 and BS 6312 became standardized.

Postmaster-General's Department

Postmaster-GeneralPostmaster-General of AustraliaPostmaster General's Department
In Australia, until 1975 the PMG, a Government monopoly, owned all telephone wiring and equipment in user premises and prohibited attachment of third party devices, and while most handsets were connected by 600 series connectors, these were peculiar to Australia so imported equipment could not be directly connected in any case, despite the general electrical compatibility.

State monopoly

government monopolystate monopoliesmonopoly
In Australia, until 1975 the PMG, a Government monopoly, owned all telephone wiring and equipment in user premises and prohibited attachment of third party devices, and while most handsets were connected by 600 series connectors, these were peculiar to Australia so imported equipment could not be directly connected in any case, despite the general electrical compatibility.

600 series connector

600 series611 sockettelephone wall socket
In Australia, until 1975 the PMG, a Government monopoly, owned all telephone wiring and equipment in user premises and prohibited attachment of third party devices, and while most handsets were connected by 600 series connectors, these were peculiar to Australia so imported equipment could not be directly connected in any case, despite the general electrical compatibility.

Hush-A-Phone Corp. v. United States

Hush-A-Phone v. United StatesHush-A-PhoneHush-a-phone Decision
It was not until a landmark court ruling regarding the Hush-A-Phone in 1956 that the use of a phone attachment (by a third party vendor) was allowed for the first time; though AT&T's right to regulate any device connected to the telephone system was upheld by the courts, they were instructed to cease interference towards Hush-A-Phone users.

AT&T Corporation

AT&TAmerican Telephone and Telegraph CompanyAmerican Telephone & Telegraph
It was not until a landmark court ruling regarding the Hush-A-Phone in 1956 that the use of a phone attachment (by a third party vendor) was allowed for the first time; though AT&T's right to regulate any device connected to the telephone system was upheld by the courts, they were instructed to cease interference towards Hush-A-Phone users.

Answering machine

answering machinestelephone answering machineAnsafone
This decision enabled the proliferation of later innovations like answering machines, fax machines, and modems.

SRI International

Stanford Research InstituteSRIStanford Research Institute (SRI)
Such modems or couplers were developed around 1966 by John van Geen at the Stanford Research Institute (now SRI International), that mimicked handset operations.

Frequency-shift keying

FSKfrequency shift keyingAFSK
A microphone and a speaker inside the modem box would pick up and transmit the signaling tones, and circuitry would convert those audio frequency-shift keying encoded binary signals for an RS232 output socket.