In All The President's Men, there's a scene where someone is repeatedly calling The Washington Post, to deny something they've done (or rather, to deny that they did it whilst in the appartment of a woman who's not his wife) and a bunch of people want to listen in on the phone call.

So they do the famous "everyone join the line together so they can all hear".

But before joining the line, some of them appear to unscrew part of the phone. What's up with that?

I assume from context that it's something about not being heard?


1 Answer 1


Ah, the ancient technology. Yes, when you had one line and everyone picked up "phone" they would all be heard. There was no "mute" button back then. You could "hold the line" which means you could not say or hear anything but the call was not ended.

Unscrewing the mouthpiece released the tension the microphone had on contacts and worked. So their breathing would not be carried and heard by the caller.

It's mechanical version of covering the mouth piece by hand. First you don't need to use your hand and two it's more foolproof as there is no microphone to pickup your breath.

  • I imagine that if everyone who unscrewed the mouthpiece instead left it in place but remained completely silent, the sound quality of the conversing parties would be worsened just by the opening of all of those microphones. No?
    – Chaim
    Apr 25, 2018 at 19:13
  • 2
    @Chaim Speaking from my own memory of such phones, having extra lines open didn't degrade the quality for those speaking/listening intrinsically, no. If someone was breathing into the phone (or other loud noises were picked up) it would interfere in the sense that other people would hear that, but simply having an extra open mic on the call didn't matter. Whether this was a result of intentional design or simply due to lesser quality microphones that weren't as sensitive as today's technology, I couldn't say.
    – Steve-O
    Apr 25, 2018 at 20:56

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