Something
public text v1 · immutableexten => s,1,Festival("Automated Nuber Lookup System. Enter the Area Code")
exten => s,1,Read(npa||3|||10)
exten => s,3,Festival("Automated Number Lookup System. Enter the next 3 digits of the number")
exten => s,4,Read(nxx||3|||10)
exten => s,5,Festival("Automated Number Lookup System. Enter the last 4 digits of the number")
exten => s,6,Read(xxxx||4|||10)
exten => s,1,AGI(callerid_shell.agi|${npa}-${nxx}-${xxxx})