We are trying to fine-tune our voice port to minimize echo on our VOIP phones. Cisco techs have been working with us, but it seems to come down to trial and error. We have a Cisco 2851 router running CME (CallManager Express).
These are settings we have tried and the results. Any audio engineers out there care to venture a suggestion? Thank you.
Input Gain Output Attenuation Result
-3......................3.....................Echo, loud and delayed
-4......................4.....................Improved, some echo
-5..................... 6.....................Worse, more echo
-4......................5.....................Improved, still some echo
Current Voice Port Echo settings:
In Gain is Set to -4 dB Out Attenuation is Set to 5 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