Something

;my config
[channels]
busydetect=1
busycount=7

relaxdtmf=yes
callwaiting=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer-yes
cancallforward=yes
callerid=asreceived
usercallerid=yes

echocancel=yes
echocancelwhenbridged=yes

;group=1            
;pickupgroup=1-4

immediate=no



signalling=fxs_ks
context=bell ; this is the conext you need in extensions.conf
channel => 1