Hardware Echo-cancellation

It is recommended to use telephony cards with an hardware echo-canceller module.

Warning

with TE13x, TE23x and TE43x cards, you MUST install the echo-canceller firmware. Otherwise the card won’t work properly.

Know which firmware you need

If you have an hardware echo-canceller module you have to install its firmware.

You first need to know which firmware you have to install. The simplest way is to restart dahdi and then to lookup in the dmesg which firmware does DAHDI request at startup:

xivo-service restart
dmesg |grep firmware
[5461540.738209] wct4xxp 0000:01:0e.0: firmware: agent aborted loading dahdi-fw-oct6114-064.bin (not found?)
[5461540.738310] wct4xxp 0000:01:0e.0: VPM450: firmware dahdi-fw-oct6114-064.bin not available from userspace

In the example above you can see that the module wct4xxp requested the dahdi-fw-oct6114-064.bin firmware file but did not found it. But you now know that you need the dahdi-fw-oct6114-064.bin firmware.

Install the firmware

When you know which firmware you need you can install it with xivo-fetchfw utility.

Use xivo-fetchfw to find the name of the package. You can search for digium occurrences in the available packages:
```
xivo-fetchfw search digium
```
Find the package name which matches the firmware file you need. In our example, we need the dahdi-fw-oct6114-064.bin file which is supplied by the package named digium-oct6114-064:
```
xivo-fetchfw install digium-oct6114-064
```

Activate the Hardware Echo-cancellation

Now that you installed hardware echo-canceller firmware you must activate it in /etc/asterisk/chan_dahdi.conf file:

echocancel = 1

Apply the configuration

To apply the configuration, restart the services:

xivo-service restart

Next step

Now that you have loaded the correct module for your card you must:

check if you need to follow one of the Specific configuration sections below,
and continue with the next configuration step which is to configure your card according to the operator links.

Specific configuration

This section describes some specific configuration. You should not follow them unless you have a specific need.

Use the Hardware Echo-canceller for DTMF detection

If you have an hardware echo-canceller you may want to use it to detect the DTMF signal (instead of asterisk).

Create the file /etc/modprobe.d/xivo-hwec-dtmf.conf:
```
touch /etc/modprobe.d/xivo-hwec-dtmf.conf
```
Fill it with the following lines replacing DAHDI_MODULE_NAME by the correct module name (wcte13xp, wct4xxp …):
```
options DAHDI_MODULE_NAME vpmdtmfsupport=1
```
Then, restart the services:
```
xivo-service restart
```