Directly working on that in AccessTM or Excel® is not possible. But you can make a detour without a problem by using Outlook®. 

Therefor create (in Outlook®) a separate contact folder and use the import function of Outlook® to import all data into this new folder.

Now work on the folder with FormatNumbers and after that export the data again into the original application.

This approach also works with other programs. It is important to know if this program provides an export format that can be imported by Outlook®. Since most current programs support the .csv type, almost all program files can be imported to Outlook®.