Public domain software to cross validate phone number area codes, zip codes and state codes. Useful in verifying or cleaning up such codes in data files. This is a command line program where the column names in the data file to be analyzed can be specified. There are no limits as to file size. Uses industry standard tab separated value (TSV) files.
.NET Control Code 128 / Code 128 GS1
.NET Control Code EAN / ISBN
Area Code Lookup - Info On Every Area Code
Free World Area Codes
Area Code Lookup Tool - Area Codes Directory