User talk:Darling
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DTMF - Dual Tone Multi-Frequency. Used for telephone signaling over the line in the voice frequency band to the call switching center. The DTMF keypad is layed out in a 4 x 4 matrix with each row representing a 'low' frequency, and each column representing a 'high' frequency.
More information A, 697 Hz ...
1 | 2 | 3 | A | 697 Hz |
---|---|---|---|---|
4 | 5 | 6 | B | 770 Hz |
7 | 8 | 9 | C | 852 Hz |
* | 0 | # | C | 941 Hz |
1209 Hz | 1336 Hz | 1477 Hz | 1633 Hz |
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