exten => 3036293337,1,SetVar(OLDEXTEN=${EXTEN})
exten => 3036293337,2,noop("got extention")
exten => 3036293337,3,noop(${OLDEXTEN})
exten => 3036293337,4,gotoif($[${CALLERIDNUM}]?callerid|1:nocallerid|1)     

exten => nocallerid,1,noop("nocallerid")
exten => nocallerid,2,Dial(SIP/triplef)

exten => callerid,1,noop("callerid")
exten => callerid,2,Dial(SIP/triplef)
exten => callerid,3,Voicemail(${EXTEN})