HI,
If you buy the hardware EC module,you should insert the module on the card.
And you only need set echocancel=yes in chan_dahdi.conf or zapata.conf to open it.
But you should comment echocanceller in /etc/dahdi/system.conf or /etc/zaptel.conf.
After that, I suggest you set a simple dialplan for outgoing. Normally, forward to file /etc/asterisk/extensions.conf, and increase these lines below to the end of this file.
[from-internal]
exten=>_X.,1,Dial(dahdi/1/${EXTEN}) // the first 1 means the first priority, and the second means from 1st channel to outside. You can customize which channel you want.
exten=>_X.,n,Hangup