zaptel.conf:
fxsks=1-4
defaultzone=us
loadzone=us

zapata.conf:
[channels]
switchtype=national
context = incoming-analog
signalling = fxs_ks
busydetect => yes
callprogress => no
busycount => 4
relaxdtmf => no
callwaiting => no
callwaitingcallerid => no
usecallerid=yes
callerid=asreceived
cidsignalling=bell
cidstart=ring
threewaycalling => no
transfer => yes
cancallforward => yes
echotraining = yes
echocancel = yes
echocancelwhenbridged = no
musiconhold = default
rxgain = 0
txgain = 0
immediate = no
group=1
channel => 1-4


ztcfg -vvvv:
Zaptel Configuration
======================


Channel map:

Channel 01: FXS Kewlstart (Default) (Slaves: 01)
Channel 02: FXS Kewlstart (Default) (Slaves: 02)
Channel 03: FXS Kewlstart (Default) (Slaves: 03)
Channel 04: FXS Kewlstart (Default) (Slaves: 04)

4 channels configured.