/etc/zaptel.conf

loadzone=de
defaultzone=de

# erster Port fuer PSTN
fxsks=1

# vierter Port fuer internes Telefon
fxoks=4

/etc/asterisk/zapata.conf

[channels]
language=de
nationalprefix=0
internationalprefix=049

;Port 1 an PSTN angeschlossen
signalling=fxs_ks
context=analog_incoming
channel => 1

;Port 4 internes Telefon angeschlossen
echotraining=yes
rxgain=0.8
txgain=0.8
callerid=12321
signalling=fxo_ks
context=default
channel => 4

/etc/asterisk/extensions.conf

[general]
static=yes
writeprotect=no

[default]

include => sip20
include => analog21
include => analog_outgoing

[sip20]
exten => 20,1,setLanguage(de)
exten => 20,n,Dial(SIP/20,25,tT)
exten => 20,n,Hangup

[analog21]
exten => 21,1,Dial(ZAP/4,25,tT)
exten => 21,n,Hangup

[analog_incoming]
exten => s,1,setLanguage(de)
exten => s,n,Dial(ZAP/4)
exten => s,n,Hangup

[analog_outgoing]
exten => _7.,1,Dial(ZAP/1/${EXTEN:1})
exten => _7.,n,Hangup