Our US customers, especially the ones using Leads management or Calls tracking applications, kept asking us about adding a functionality that automatically fills in the time zone according to the area code for the US phone numbers as it would save them a great deal of time by instantly displaying timezones next to the phone numbers.

We created a sample Area Code to TimeZone mapping application to demonstrate this functionality. Please explore the application and review a Setup mode.
The application is based on two tables joined via many-to-many relationship.
"Phones" table contains sample phone number list along with the State/Time Zone offset extracted from the "Mappings" table.
Area code is intelligently extracted from the US phone number regardless of the format.
"Mappings" table contains mapping between the US phone number area code and the timezone.
Now you may add area code to time zone mapping functionality to your existing applications or hire us to do it for you.