Morlan,
Your profile doesn't give your location, but just as an aside (if you're in America or if anyone reading this is) for about $25 you can purchase, on-line, from several sources, an Access table with area codes, zip codes, cities/states and longitudes/latitudes. By having your users enter just the zip code you can automatically fill in the city, state and area code fields for the record. This saves a great deal of data input time for the user, and as well as guarantying the correct entry for city/state/area code.
The Missinglinq