People have come up with very elaborate explanations for how Facebook obtains recommended friends (see: https://graziadaily.co.uk/life/real-life/facebook-suggested-friends-work/ The truth is very simply obtained, I am not a Facebook user so I decided to set up an fictitious email address unrelated to my personal information on a personal computer. I thus proceeded to sign up to Facebook with a similar fictitious name and used my personal phone number to receive an SMS message to activate it. Upon activation I noticed my entire contact list and those who have added me to their contacts (which I did not reciprocate) appeared as "Recommended Friends." I encourage you to do the same thing to verify. In order for this to occur, without a chance of your information being volunteered to Facebook, you must not have Instagram linked to your contact list and you must not use Facebook mobile applications. This is a blatant violation of Terms of Service contracts for both Verizon Communications and Facebook Inc.. Another important note, your contacts list may be synced to your Google account but their privacy policy also protects your personal information from third-parties. The official response from Verizon Wireless support staff is that once you give your telephone number to a third-party they reserve the right to violate your terms of service contract and sell your personal information. Official response from Facebook is that they will not import your contact list information without your permission and only when using the mobile application. By verifying the above process of Facebook account creation you will become aware that both of these companies and likely other telecommunication networks are profiting from your personal information.