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?
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