This week a TechCrunch article revealed that Facebook is using phone numbers users have provided as a security measure for two-factor authentication as a way to send targeted ads to those users.
If that's not a thing you want to happen (and you shouldn't), you can get around the problem by removing your phone number from the site and setting two-factor authentication up using an authentication app instead.
Facebook is kind of a mess right now. And there are plenty of equally messy reaction pieces cajoling you and everyone you know, to delete your account in a massive middle finger to the web's prevailing social network. That's the easy take and, honestly, we've experienced this mob response before. Did you #DeleteFacebook then? Me neither.
To remove your phone number from Facebook go to the Settings menu on your account (you get there by clicking the arrow at the top right side of the page) and then Your Facebook Information followed by View under the Access Your Information label. Within that menu, you'll want to select Profile Information and then Your Contact Information. When you see your phone number, hit that delete button.
Afterwards, select Security and Login from that main Settings page and then Set up two-factor authentication. From there you should be able to customise your two-factor settings, specifically so that you're using an authenticator app (such as Google Authentication) rather than your phone number for that extra layer of security.