Using two-factor authentication is, arguably, the best way to protect your Facebook profile. How to do it without giving your cell phone number
Two Factors Authentication (2FA) via cell phone number is certainly a quick and easy way to protect our privacy on the web (even if you have to be careful about phone number theft). In recent days, however, we have discovered that Facebook has been using our personal numbers to send us targeted advertising and more.
Some journalists, in fact, have noted that the social network does nothing to protect this sensitive data even allowing almost any user to search our phone number and find our profile. For this reason, using the phone number as a "second factor" of authentication is perhaps not the most appropriate choice, if our goal is to protect our data and our privacy. But how can we protect our Facebook account without giving our phone number to Zuckerberg, who certainly doesn't use it as we would like?
Apps for two-factor authentication
A good way (until later disproved, of course) is to use a specific app for authentication. Like Google Authenticator or Duo Mobile, for example. With these apps we can keep the two-factor authentication, necessary to prevent those who manage to steal our login and password to get possession of our Facebook profile, but without being forced to surrender our number.
How two-factor authentication apps work
Both Google Authenticator and Duo Mobile can be downloaded from the Play Store and work on the same principle: instead of using a code sent via SMS as a second authentication factor, you use a code provided by the app. In the case of Duo Mobile the code is sent from the service to the app installed on your phone, in the case of Google Autenticator it is the app itself that contains a code generator that works even when your smartphone is offline. Both systems, then, protect you in case someone is trying to access your Facebook profile from a device that isn't your smartphone.
Performing 2FA authentication to Facebook via an app is certainly more inconvenient than doing so by receiving a text message. But, since Mark Zuckerberg's company has now clearly demonstrated that it has no intention of defending our privacy, perhaps it's already a forced choice. Also because in the not too distant future we will see a tight integration between Facebook, Messenger, Instagram and WhatsApp and it is very likely that Zuckerberg will ask to use our phone number as a unique ID for the future mega-platform.