File:NIE 1905 Telephone - simple switchboard circuit.jpg

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Description	English: Diagram of simple metallic circuit switchboard: When a call is received the current coming in on the line wires causes the drop to fall, thus announcing the number of the subscriber. The central operator then inserts the answering plug in the jack, and, pressing the listening key, puts her instrument in circuit. She then inserts the calling plug in the jack belonging to the line of the desired subscriber, and by pressing the ringing key sends a signal to the latter's instrument.
Date	published 1905
Source	“Telephone,” The New International Encyclopædia, v. 19, 1905, p. 103.
Author	unknown author

Public domain	This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.	United States
	This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.

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	Date/Time	Thumbnail	Dimensions	User	Comment
current	22:32, 29 August 2017		772 × 320 (73 KB)	Bob Burkhardt (talk \| contribs)	{{Information \|Description ={{en\|1=Diagram of simple metallic circuit switchboard: When a call is received the current coming in on the line wires causes the drop to fall, thus announcing the number of the subscriber. The central operator then inse...

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