/etc/asterisk/zapata.conf:

[channels]
language=en
usecallerid=yes
callerid=asreceived
echocancel=yes
echocancelwhenbridged=no
echotraining=900
adsi=no
faxdetect=no
switchtype=national
signalling=pri_cpe
context=incoming
group=1
channel => 1-23

/etc/zaptel.conf
span=1,1,0,esf,b8zs
bchan=1-23
dchan=24