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This only applies to servers using T1/PRI or analog cards without built-in hardware echo cancellation (HWEC) hardware, and is irrelevant for VoIP-only servers. Cards without HWEC are fairly rare and mostly date to before 2009.
Echo parameters and troubleshooting
To view echo parameters access the web admin interface for the users system and select the Options -> echo page.
Make sure the user changes echo settings when there is no call volume so the settings take effect and a test call can be placed afterward.
Send Volume
Decreasing the send volume on a call helps reduce the amount of echo returned to the system. To troubleshoot echo have the user perform the following steps.
Open the web admin interface
Select the Options -> echo page
Decrease the send volume. In most cases -2 dB or -4 dB are enough
Apply the changes, you may have to reset your server in the Options -> reset server page to implement the changes (this is because the changes require a software restart and if users are on calls the software will not restart when you update.)
Place test calls to see if the problem has been resolved/reduced.
Echo Taps
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Note: a default value of "yes" is equal to 128 echo taps |
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Open the web admin interface
Select the Options->echo page
Change the echo taps based on the diagnosis of where the echo is coming from (below)
Place test calls to see if the problem has been resolved/reduced.
If the echo is caused by a device that is close
Lower the number of echo taps.
Example: Analog-to-digital line converter in the building
If echo is only experienced on long distance calls
Increase the echo taps to 256 or to 128 if it was set lower
TDM Bridged Echo Cancel
Toggle this setting if bridged calls are having problems
Example: conference bridges, attended transfers.
Echo Training
Echo training is the amount of time in milliseconds the system spends before connecting the call to try and train out the echo. The default ("yes") is the best setting in most cases. Try other troubleshooting steps before altering this setting as it will have the least noticible or no effect on your call quality.