multifrequência de tom dual(The signaling system used in telephones with touchtone keypads, in which each digit is associated with two specific frequencies)
dual-tone multiple-frequency The signaling system used in telephones with touchtone keypads, in which each digit is associated with two specific frequencies
Dual Tone Multiple-Frequency(The signaling system used in telephones with touchtone keypads, in which each digit is associated with two specific frequencies)
