 |
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| dual-tone multiple-frequency (The signaling system used in telephones with touchtone keypads, in which each digit is associated with two specific frequencies) | |||
| Polaco tesauro | |||
| |||
| DTMF | |||
|
| |||
| dual-tone multiple-frequency (The signaling system used in telephones with touchtone keypads, in which each digit is associated with two specific frequencies) | |||
| Polaco tesauro | |||
| |||
| DTMF | |||
