Multi-Tech Systems MT3334HD8 - Manual (Page 76)

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