We recently tried to re-activate a copy of Office 2010 that was legitimately purchased. However, the automatic internet activation failed. So we hit the “Back” button and chose “Telephone activation.” We were greeted with the error message

“Telephone activation is no longer supported for your product” 

Yikes! What to do now?

What we discovered was that telephone activation still works it is just that Microsoft is hiding the phone numbers! For activation in the United States, the activation phone number is

866-421-7141

It will work as it used to work.

For other countries, you can look up the phone numbers here

Phone numbers for Microsoft telephone activation