Something

[channels]
language=en
;

usecallerid=yes
hidecallerid=no
transfer=yes
cancallforward=yes
callreturn=yes
echocancel=64
echocancelwhenbridged=no
;echotraining=100
rxgain=0
txgain=0

group=1
signalling=fxo_ks
context=doorphone
immediate = yes
callerid = "Door" <125>
channel => 1-4
callgroup=1

group=2
signalling=fxs_ks
context=bella-main
channel => 5-7
callgroup=1