MT3334HD8 User Guide
Figure B-2. Standard 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.
Hz
697
770
852
941
Hz
Figure B-3. Extended DTMF frequencies
70
Digits
1
2
3
4
5
6
7
8
9
*
0
#
1209
1336
1477
A
B
C
D
1633
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