WE E5 208 Key Set
1930
Siemens and Halske 25-extension intercom
1920
Dictograph Telephone Switchboard
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Dictograph ProductsDictograph ProductsDictograph Products Corporation, founded in 1902 as General Acoustic, was a maker of office intercoms, surveillance devices, hearing aids and radio equipment. Dictograph invented some of the earliest practical hands-free office intercoms and audio-eavesdropping devices. Utilizing a highly sensitive 'Metrophone' microphone diaphragm, their "Detective Dictograph" (not to be confused with Edison's 'Dictaphone') could pick up conversations from across a room without the speaker needing to be near a mouthpiece. It was famously used by police departments and investigators across the country. The company also adapted its sensitive microphone tech into office spaces, building high-end, luxury desktop intercoms for corporate executives. Their major selling point was that you could talk completely hands-free while walking around your office, and the audio would boom out of a loudspeaker. · Office phones, American · Source/via: Pioneers
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