🚀 go-pugleaf

gt8741b@prism.gatech.edu (Chris Adams) writes:

>Can someone tell me what the frequencies of the buttons on a telephone generate
>and what the dial tone frequency is?  I am trying to build something, and I
>need to recognize a dial tone, and generate button presses.
>--
>Chris Adams                       | "If tin whistles are made of tin,
>Georgia Tech                      |  what do they make foghorns from?"
>Internet: gt8741b@prism.gatech.edu|       --  Lonnie Donegan
>----------------------------------+ 

I don't recall the tone frequencies.  However, they are easily found in
the published ISO, British and Australian standards.  Presumably these,
or the USA equivalent should be easily obtainable.  Basically, each
digit (as well as the * and # functions) are composed of 2 frequencies
sounded together.  All keys in the same Column share the same lower tone
(with the lower tone ascending across columns) ... and similarly for the
rows.




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