Echo problem - fxotune doesn't help much

I have a TDM400p connected to PSTN via a FXO module. Before running fxotune, there is a slight echo problem. However, after I run the original (unpatched) fxotune -i 4, and fxotune -s, the echo is even worst.

I then patched fxotune and rerun fxotune -i 5, and fxotune -s, the echo seems to be improved a lot if I increase rxgain and txgain over 8.0 in zapata.conf. However, ocassionally there is a very loud noise that last for about 5 seconds at the beginning of the communication. I guess the noise is the echotraining and it is so loud that I need to take the handset off my ear!

I am quite disappointed with the TDM400P echo problem because I also used a X100P clone and it works without using any fxotune and there is no echo problem with X100P clone, with cost less than 10% of a TDM400p card!

Anyone can help to fix the TDM400p echo problem?


Echo solutions can be found in knowledge database:

try switching the echo canceller to Mark2 and enable aggressive echo suppression. it will eat more CPU but in my experience produces a good result. One client complained of a transient echo that would pop up half the time (probably due to crap POTS lines), aggressive echo can cleared that right up and they ahve been happy for a long time.

see for instructions-

it’s been a while since i had to tackle echo … but i do recall the aggressive option resulted in very “clipped” audio … UK users would call it the “Norman Wisdom effect”. i take it you haven’t had that issue ?

haven’t heard any complaints yet. The few times I’ve used it on TDMxx series cards, customers report huge increase in call quality due to lack of echo. Haven’t heard any complaints about clipped audio yet, and when i test them they always sound fine, no audio quality problem that i could tell.

I’ve tested all the echo cancellers (steve, steve2, makr, mark2, mark2 + aggressive suppressor, mark3, kb1, mg2) and found that only mark3 and mark2 with aggressive suppressor eliminates echo!! but I think I encounter the problem that baconbuttie experienced with aggressive option, and therefore, mark3 is my only choice.

It surprised me that kb1 and mg2 (which I think is a more recent echo cancellation addition to Asterisk) are not working as good as mark3. I do suggest anyone experiencing echo problem to try ALL echo cancellors. This is time consuming but I think you may be amazed by the result.


Echo problem fixed!!! I changed my motherboard and CPU with an Intel Celeron 566 system and the echo problem is gone!! Just build everything out of default and echo problem is gone!!

I think the echo cancellation really relys on FPU processing and VIA C3 CPU is not doing a good job.