I believe the Kraftwerk song "Pocket Calculator" is actually about a "Blue Box", the device that phone phreaks used to place telephone calls back in the days of in-band signalling.
The dial of a touch tone telephone puts out a certain set of frequencies, but the telephone operator's dial put out a set a frequencies that directly controlled the Long Lines telephone network. The Blue box duplicated the operator's frequencies. http://CheshireCatalyst.Com/bluebox
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