3com MSR 20-20 참조 매뉴얼

Use the dtmf threshold command to configure the sensitivity of DTMF digit 
detection.

Use the undo dtmf threshold command to restore the default.

The dtmf threshold command issues the thresholds for DTMF dial tone detection 
to the underlying layer DSP for the purpose of tuning detection sensitivity and 
reliability of the device subtly. Inside the DSP, a set of generic default values have 
been configured. They are 1,400, 458, -9, -9, -9, -9, -3, -12, -12, 30, 300, 3,200, 
375, with their index being 0 through 12. Professionals can use this command to 
adjust the device when DTMF digit detection fails. In normal cases, the defaults 
are adopted.

# Set DTMF threshold 9 in voice subscriber line 1/0.

<Sysname> system-view

[Sysname] voice-setup

[Sysname-voice] subscriber-line 1/0

[Sysname-voice-line1/0] dtmf threshold analog 9 40 

echo-canceller { enable | tail-length milliseconds }

undo echo-canceller { enable | tail-length }

FXS/FXO/E&M voice subscriber line view

enable: Enables the echo cancellation (EC) function.

10 

The frequency of the first extra 
frequency point specified for 
detection.

In addition, it must be a frequency 
100 Hz greater than or less than the 
row and column frequency groups. 

300 to 3,400 Hz, 
with a default of 
300 Hz. 

- 

11 

The frequency of the second extra 
frequency point specified for 
detection.

In addition, it must be a frequency 
100 Hz greater than or less than the 
row and column frequency groups. 

300 to 3,400 Hz, 
with a default of 
3,200 Hz. 

- 

12 

The lower limit of the amplitude of 
the input signal. The average 
amplitude must be greater than this 
threshold for the input signal to be 
recognized as a DTMF digit. 

0 to 700, with a 
default of 375. 

The larger the value is, 
the higher the detection 
reliability is. However, 
the sensitivity drops.

Table 682   Meaning of the index numbers