If you have used the “Contact Sync” tool on Facebook to coordinate your cell phone address book with your Facebook friends list, you may have unknowingly provided the world’s most powerful social network with your phone’s contact list.
The “Contact Sync” tool synchronizes your friends’ Facebook profiles with your phone’s contact list. The application adds Facebook profile pictures and other personal information to your phone’s address book.
However, this synchronizing of personal data flows two ways.
According to a report in the Guardian, Contact Sync also uploads all of your contacts’ phone numbers and names to Facebook.
People who want to find out if their phone’s address book has been uploaded to Facebook can visit Facebook’s Phonebook Page.
Although the Contact Sync app warns people that their phonebook will be uploaded to Facebook, privacy advocates worry that the warning is worded in such a way that most users will ignore it. If your Facebook privacy settings aren’t set properly, your phone book could be accidentally made public.
[ Source: The Guardian ]