On a Cisco 2851 router / Call Manager Express, we have our T1 Voice line set as follows:
In Gain is Set to 0 dB Out Attenuation is Set to 0 dB Echo Cancellation is enabled Echo Cancellation NLP mute is disabled Echo Cancellation NLP threshold is -21 dB Echo Cancel Coverage is set to 64 ms Echo Cancel worst case ERL is set to 6 dB
We are getting a lot of echo on calls to external analog phones.
We have tried different settings on the ERL, Echo Cancel Coverage, Input Gain and Output Attenuation. So far nothing works to diminish the echo. Cisco IOS version is 12.3(11).
Please advise. Thank you.