3com MSR 20-20 참조 매뉴얼

Use the undo echo-canceller command to restore the default.

By default, the convergence rate of comfort noise amplitude is 0, the maximum 
amplitude of comfort noise is 256, the comfort noise mixture proportion control 
factor is 100, and the threshold of two-way talk is 1.

# Set the convergence rate of comfort noise amplitude to 50.

<Sysname> system-view

[Sysname] voice-setup

[Sysname-voice] echo-canceller parameter convergence-rate 50 

em-phy-parm { 2-wire | 4-wire }

Analog E&M voice subscriber line view

2-wire: Chooses the 2-wire analog E&M wire scheme.

4-wire: Chooses the 4-wire analog E&M wire scheme.

Use the em-phy-parm command to configure a wire scheme for the analog E&M 
subscriber line.

Use the undo em-phy-parm command to restore the default.

By default, the 4-wire analog E&M cable is selected.

This command is only applicable only to the analog E&M subscriber line. The 
configuration will apply to all E&M interfaces of the card after you configure this 
command.

# Choose the 4-wire scheme for the analog E&M subscriber line.

<Sysname> system-view

[Sysname] voice-setup

[Sysname-voice] subscriber-line 1/0

[Sysname-voice-line1/0] em-phy-parm 4-wire 

em-signal { delay | immediate | wink }