Mine

[channels]
context = incoming
language = en
signalling = fxs_ks
;rxwink = 300
usecallerid = yes
hidecallerid = no
rxgain = 0.0
txgain = 0.0
cidsignalling = bell
cidstart = ring
callerid=asreceived

callwaiting = no
callreturn = no
immediate = no
echocancel = no
echotraining = no
;busydetect=yes
echocancelwhenbridged = no

group = 4
channel => 1-24