On the old dial telephones you had a white button in the bottom corner.
I never understood what the function of that button was, because when we pressed it as a child, nothing happened.
Coincidentally today we were talking about it at work, and no one had any idea of the function.
Now my interest has been aroused again in this enigmatic button from my youth.
Polite greetings
Glenn Wouters
Answer
Bye Glenn
What a wonderful question, I remember that button too…
The answer is this: the earlier telephones with a dial had far fewer options than we are used to today. There was no ‘asterisk’ or ‘hash’, and no ‘repeat’ button. Yet there were also (early) telephone exchanges for within a company, their own exchanges. Well, that little white button was meant to be ‘forward’. Such a telephone was connected to the normal network with two wires and that button had no function whatsoever. But at a company telephone exchange there was a third wire, the ground wire. And with that button you brought 1 of the other two wires to ground potential. The exchange then put the ongoing call on hold, and returned a dial tone. Now you could dial another internal number and transfer the ongoing call to that other number. So it was an ‘earth test’, to transfer calls at an indoor switchboard.
Answered by
Tony Vandenborn
electronics, telecommunications
UC Leuven Andreas Vesaliusstraat 13 | 3000 Leuven Hertogstraat 178 | 3001 Heverlee UC Limburg Campus Diepenbeek, Agoralaan Building B bus 1 3590 Diepenbeek
http://www.ucll.be
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