Re: Tone frequencies on telephone

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Article #14652

#14652

From: Scott Fraser
Date: Tue, 17 Nov 1992 20:27

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In article <1992Nov17.075719.23612@riacs.edu> 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.
>--

For TOUCH-TONE or TOUCH CALLING, the following is true,

Low     |
 Group  |
 (hertz)|
        |
--------|-------|-------|-------|
697     |   1   |   2   |   3   |
--------|-------|-------|-------|
770     |   4   |   5   |   6   |
--------|-------|-------|-------|
852     |   7   |   8   |   9   |
--------|-------|-------|-------|
941     |   *   |   0   |   #   |
--------|-------|-------|-------|---------------------
        | 1209  | 1336  | 1477  | High group (hertz) 

Each digit is composed of one frequency from the low group and one frequency
from the high group.  The frequencies have been chsen to minimize voice
simulation.

If you are using another system, the above chart will not hold true, but this
is what is found in 'most' phones here in the US.

Scott

Standard disclaimers apply!

Technical Details

Message-ID: <1992Nov17.202743.12624@elroy.jpl.nasa.gov>

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From: fraser@praha.jpl.nasa.gov (Scott Fraser)
Subject: Re: Tone frequencies on telephone
Message-ID: <1992Nov17.202743.12624@elroy.jpl.nasa.gov>
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Date: Tue, 17 Nov 1992 20:27:43 GMT
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