Sorry about the formatting. I tried to use LaTeX formatting codes, but to no avail... =8(
If you look at this table, which I tried to layout what issues the problem states, there are only two possible
types of calls that can be made: outside the caller's area code and any other call. The only other possibility is that there is no call made, as indicated.
Not sure if laying it out this way gives you a better understanding of decision tables or helps at all with this problem. Try looking up logic or truth tables and/or Algebraic/Boolean Logic on the 'net. It might give you a better understanding.