How does a Touch-Tone phone fight background noise interference?

My father worked for the telephone company and he would occasionally demonstrate how phones worked. One lesson I remember is how you could use sound to dial phone numbers. I was pretty young, so this seemed like magic to me, but my sister who was older, wiser and more inquisitive asked if it was possible for the phone to hear a noise and dial a number by mistake. He explained how this was not easy because when you pushed the button you were actually “hearing” two tones being played at the same time.

I had always remember him saying this, but never really delved deeper into what he meant until yesterday when I was reading an old copy of Popular Mechanics and found this explanation that sums up the lesson I think he was trying to teach us.



The Retroist

Editor/Podcaster at Retroist
The Retroist is like a BBQ on a bun without the bones. You're only human daddy. Chomp!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

5 thoughts on “How does a Touch-Tone phone fight background noise interference?”

%d bloggers like this: