exten => _NXXXXXXX,1,Dial(ZAP/g1/${EXTEM},,T)
exten => n,NoOp( Dial Status: ${DIALSTATUS})
exten => s,n,Goto(menu-${DIALSTATUS},s,1)

[menu-ANSWER]

[menu-NOANSWER]

[menu-CONGESTION]

[menu-CANCEL]

and so forth