Multitech MT2834MR6 Betriebsanweisung PDF herunterladen (Seite 93)

Appendix

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 four low-frequency tones (697, 770, 852, 941 Hz), while

the three vertical columns use three high-frequency tones (1209, 1336, 1477 Hz). The tone frequency

tolerance is ± 0.02%.

For example, the digit 4 is dialed by combining two tone frequencies: 770 Hz from the second row, and 1209

Hz from the first column. In another example, the digit 9 is dialed with tone frequencies 852 Hz and 1477 Hz.





























Figure B-2. Standard DTMF frequencies Figure B-3. Extended DTMF frequencies

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 that are provided depend on the PBX manufacturer’s implementation and

feature set.

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Multitech MT2834MR6 Betriebsanweisung Seite 93