MT2834ZPX Owner's Manual
Appendix B - Tone Dial Frequencies
The tone-dialing method combines two frequencies for each of the twelve digits found on a Touch Tone dial pad. This method is referred to as Dual-Tone Multi-Frequency (DTMF) dialing. The four horizontal rows on a Touch-Tone keypad use the four low frequencies (697, 770, 852, 941 Hz), while the three vertical columns use the three high frequencies (1209, 1336, 1477 Hz). The generally accepted tone frequency tolerance is +0.02%.
For example, the digit 4 would be dialed by combining two tone frequencies. It would use the frequency 770 Hz from the second row, and the frequency 1209 Hz from the first column. In another example, the digit 9 would be dialed with the tone frequencies of 852 Hz and 1477 Hz.
The extended DTMF characters (A, B, C, D) are the high-end frequencies (1633 Hz) defined on some telephone sets with a fourth vertical column of buttons. This fourth column provides for extended PBX control functions; the actual functions provided are dependent on the PBX manaufacturer's implementation and feature set.
