Tech Info - DTMF Tones

The following table defines the tones used in DTMF (see ANSI T1.401-1988 Section 7.2):

Each tone is composed of a low-high pair of frequencies as defined in the table:

DTMF Char	Low (Hz)	high (Hz)
1	697	1209
2	697	1336
3	697	1477
4	770	1209
5	770	1336
6	770	1477
7	852	1209
8	852	1336
9	852	1477
* (star)	941	1209
0	941	1336
# (num)	941	1477
A	697	1633
B	770	1633
C	852	1633
D	941	1633

DTMF Tone Power is given by the following table:

Power	dBm
Max. Power per tone	+1.0
Min. Power per Low freq. tone	-10.5
Min. power per High freq. tone	-8.5

Notes: frequency limit is +- 1.5%, difference in power between the low and high frequencies should not exceed 3dB and the power of the high frequency tone should equal or exceed the low frequency tone.

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Tech Info - DTMF Tones

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