[trunk-in]
exten => _[+]ZX.,1,Verbose(3,incoming call from ${CONTEXT} for destination ${EXTEN})
exten => _[+]ZX.,n,Goto(public,${EXTEN},1)

[trunk-out]
exten => _[+]ZX.,1,Verbose(3,outgoing call in context ${CONTEXT} to destination ${EXTEN})
exten => _[+]ZX.,n,Dial(IAX2/pbx0.l--n.de/${EXTEN})