Int B3 Fn 80  - Zipkey V2.0+ - Determine State For Area Code               [U]

   AH = 80h
   BX = telephone area code (decimal)

Return: CF clear if successful
       AL = ZIPKEY state code
       DX = first ZIP region for state (03E8h if Canada)
       CX = number of ZIP regions in state
   CF set on error
       AL = FFh
       DX = 03E9h