Asterisk recording echo


i have a problem with exhos on mixmonitor recordings. our agents are using vaxvoip softphone and x-lite without any complaints with echos and other sound artifacts, at the same time when using chanspy there are alot of echos, artifacts in the audio. This also applies for recording.

any ideas where i should start searching for a solution?

local asterisk, voipprovider or somewhere else. Could this be solved by using t1, pri or some other tehnology. im using sip - sip. gsm on our side and u-law towards voipprovider.

/ Marcus

You need two for echo…one side generates the echo the other side suffers from it…
I guess that in your case your agents are generating the echo and the people they talk with hear the echo.

For more information on the nature of echo in VoIP and ways to deal with it, take a look at the following blog post

thanks for the answer, though i dont think its the answer im looking for.

pstn <-> sip-trunk voip provider <-> asterisk recording calls <-> agents

in asterisk recordings, the agent audio quality is good, audio from sip-trunk voip provider is bad with echo, hissing and other sound artifacts.

and what im looking for is the possible source of the problem/problems

The problem is with the VOIP provider. Echo cancellation should be done at the PSTN boundary. The other artefacts may be due IP performance issues.

In order to analyze it further could you please verify:

Do the agents hear the echo during the calls ?

If the two participants in the call are using headsets do you still have echo in the recording ?


the agents do not hear the echo to the extent that there is complaint. the agent participant is using headset, the other participant is from external call from voip-provider which often is from pstn.

/ Marcus

Strange indeed. Maybe the problem you are facing is related to the recording mechanism ?

In order to verify if the problem is indeed related to the recording itself, could you please record the calls using a different recording mechanism ? If you do not have any other recording tool available, you can record the calls using Personal PBXMate.

Does the new recording contain echo as well ?

the main problem seemed to be that we used Auto gain control and mic boost on our agent softphones, and also a part of the problem could have been that i by mistake put ptime to 10 on a-law codec.

/ Marcus