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MT2834ZPX Owner's Manual
Appendix B - Tone Dial Frequencies
Hz Digits
697
770
852
941
Hz 1209 1336 1477 1633
1 2 3 A
4 5 6 B
7 8 9 C
0 # D
*
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.