I am using a Digium TE220 set for Europe.

/etc/modprobe.d/dahdi.conf
options wct4xxp default_linemode=e1

/etc/asterisk/chan_dahdi.conf
[channels]
language=en
busydetect=yes
busycount=10
usecallerid=yes
callwaiting=yes
usecallingpres=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=no
echotraining=no
immediate=no
faxdetect=no
rxgain=0.0
txgain=0.0