Here is another config file on a working pbx (7 lines)

; Span 1: WCTDM/0 "YSTDM8xx REV E Board 1"
;;; line="1 WCTDM/0/0"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-zaptel
channel => 1
context=default

;;; line="2 WCTDM/0/1"
signalling=fxs_ks
callerid=asreceived
group=0
context=from-zaptel
channel => 2
context=default

;;; line="3 WCTDM/0/2"
signalling=fxs_ks
callerid=asreceived
group=1
context=from-zaptel
channel => 3
context=default

;;; line="4 WCTDM/0/3"
signalling=fxs_ks
callerid=asreceived
group=1
context=from-zaptel
channel => 4
context=default

;;; line="5 WCTDM/0/4"
signalling=fxs_ks
callerid=asreceived
group=1
context=from-zaptel
channel => 5
context=default

;;; line="6 WCTDM/0/5"
signalling=fxs_ks
callerid=asreceived
group=2
context=from-zaptel