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Wednesday 25th May 2016
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Why do we "tap" phones?


Where does the phrase "phone tapping" come from?
Patrick, Mitcham


** Definitive **
Name: Keith, Bond Street
Qualification: Horologist
Answer: I’m sitting in front of my tap and die set, which is used to make the thread that goes into screws. The tap screws into the plate to make the thread, so tapping into it gets into the watch. Tapping a phone call is to get into the conversation.

Name: Robert, Rochester
Qualification: My Dad did this!
Answer: BT engineers used to be able to climb up poles and tap across the lines to listen in and the piece of equipment – the field phone – was called a “tapper”.
(James O’Brien: You might be right, but I suspect the tap bit came from plumbing originally.)