Callcentric offers the ability to add a caller's phone number directly to one's phonebook. Once the number is added, there is no indication that a caller is in the phonebook.
This extension shows a phonebook icon next to the numbers that have been added to the phonebook. The number is also changed to gray to help give numbers that are not in the phonebook more emphasis so that one can quickly know which numbers might need to be added.
The extension currently works on the dashboard and the "Calls Received" and "Calls Made" pages.