Users are complaining that they hear echo when they place calls to the PSTN through the
HQ_PSTN gateway. The voice port configuration for the gateway is as follows:
voice-port 1/0:23
input gain -1
output attenuation 1
echo-cancel erl worst-case 3
Why are users hearing echo?

Select the best response.

A.
The echo canceller is functioning properly and some echo is to be expected on every call.

B.
The actual ERL is 2dB; however, the echo canceller still does not acknowledge the input signal
as echo because it is lower than the echo-cancel erl worst-case 3 command.

C.
The echo canceller should be configured so that SIN and SOUT have a 2 dB difference in order
to function properly.

D.
InSignalLevel needs to be adjusted so that it is within the range from -20 dB to -25 dB