Fighting Echo on POTS lines

Using fxotune will help echo canceller to work better.

Do this before setting up echo canceller, it means to disable echo canceller options in /etc/dahdi/system.conf and
/etc/asterisk/chan_dahdi.conf, and to stop asterisk but dahdi still running.

follow the following step by step:
1. Stop asterisk: /etc/init.d/amportal stop
2. Stop dahdi: /etc/init.d/dahdi stop
3. Remove echo related options to disable echo canceller:
3.1. edit /etc/dahdi/system.conf and set echocanceller=none for all channels

by default it’s like this: echocanceller=oslec,1
change to this:

3.2. edit /etc/asterisk/chan_dahdi.conf and set the echo parameters like this:

;echotraining=800 ; disabled when using OSLEC
echocancel=yes ; yes=128. you can use any power of 2 such as 128,256,512,1024

4. Start dahdi: /etc/init.d/dahdi start
5. Plug the line to FXO
6. To get echoes information on FXO lines run # fxotune -i 4 (use 4, its any number, but 4 is on all over documents)
7. Once done (2-3 minutes per line/per FXO port), take a look for /etc/fxotune.conf and read the content, it should have some sort of configurations or options
8. To apply tuning run: # fxotune -s (this will be automatically executed by dahdi init, so you dont need to do this everytime)
9. Enable echo canceller options (do not enable on dahdi if you’re using hardware echo canceller, only echocancel=yes)
10. Run asterisk, normal execution, reboot the server or just run /etc/init.d/amportal start

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