DAHDI_ATTACH_ECHOCAN failed on channel 1: Invalid argument (22)

Currently, on a new install of the latest FreePBX, the DAHDI module has some problems with echo cancellation on FXO/FXS cards. This will cause the module to not load correctly. This may be fixed in the future.

First and foremost, reboot. I’ve had it to where I run dahdi_cfg and it produce this error when setting hwec as the canceler. A reboot fixes it.

DAHDi seems to want to use oslec echo canceler by default, however it’s not a module that’s normally loaded. There are 2 solutions to this issue. First is to use the MG2 echo canceler. This is the easiest, however, the oslec echo canceler is actually better. I will go through both:

## Change to MG2 Echo Canceler:

sudo vi /etc/dahdi/system.conf

Change the line:

echocanceller=oslec,1,2

to:

echocanceller=mg2,1,2

You’re line may vary based on how many channels you have.

Run the config again with some output, it should work now:

sudo dahdi_cfg -vvvvv

## Fix OSLEC Echo Canceler:

I haven’t been able to get it work yet… stay tuned.