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Echo, step by step guide

Echo can be caused by either acoustic feedback or electrical imbalances in impedance, either way you should be able to resolve most causes or at least pin point where your system is failing.  We have put together this step by step procedure to help you isolate the issue and then take steps to resolve it.

Locating the cause of echo.

Since we know that the two causes of echo are acoustic and electrical the first step in isolating the cause of the echo is to try to determine who widespread the problem is, how often it occurs and is it acoustic echo.

Determine if the echo is acoustic feedback.

Typically acoustic echo will be continuous with certain words being noticed more than others.  Both ends will hear the echo.

  1. Is the echo on all phones or just one or two?  The first step would be to simply hold your hand over the speaker in the handset.  Does that stop or reduce the echo?  Change out the phone, as some cheap phones can have faulty insular separation that allows voice to travel inside the handset from the ear speaker back to the mouth piece.  Adjust the volume of the phone, although this can lower echo that is actually due to impedance on down the line, it can be a useful way to test for acoustic feedback.
Electrical induced echo.

Echo can be frustrating, but taking it one step at a time, you should be able to locate the root cause.Echo caused by an impedance mismatch or other electrical cause will likely result in echo that is strong on the VoIP callers side, but unnoticeable on the far end.  more

The first step in determining if the echo is local (inside the premise) would be to look for and eliminate any faulty connections and electrical interference.

If the echo stops when the house wiring is eliminated the cause is to be found in one of the following:

Echo that is not acoustic or caused at the premise.

If after eliminating the above, you still experience echo, then it is likely the echo is being caused by improper echo cancellation on the PSTN gateways.  Understanding that echo only becomes noticeable when there is a delay between speaking and hearing your voice echoed, the longer the delay the more noticeable the resulting echo.  Traditional PSTN connections have echo, due to delay, but echo cancellation is used for long distance PSTN calls.  Additionally, echo cancellation is used on all cellular calls to the PSTN.  Here are some things to look for:

If you are able to access settings in your ATA or are using Asterisk you should be able to reduce echo by tweaking some settings. 

If your echo is the type that leaks from the incoming voice to the outgoing voice then some ATAs have TX and Rx Gain adjustments that can be used for the analog FXO port. 

For more about Asterisk settings we suggest you go to VoIP Wiki