Anonymity on Facebook - how do they suggest people I should know?

  • I want to know how Facebook discovers the people who you know in real life or who know you.

    I tried the following to see if Facebook can still discover my acquaintances in real life and suggest them to me as a friend.

    1. I connected using a VPN (an anonymous VPN, not one of those free VPN services). I have confirmed that it does not leak my actual IP address.
    2. I cleared the cookies in my browser (specific to sites like Facebook, Google, and Yahoo) and started a fresh instance of Browsing Session. Anyway, cookies specific to Facebook only should matter, and I cleared them all.
    3. I registered an email account with an email service provider who does not require a mobile number for registration. I used an email ID name which had no resemblance to my real name. I did not mention anything related to my geographical location while registering the email address. Please note that this was a fresh email address, and I have never used it to send an email or receive an email.
    4. Now, I registered on Facebook, using a name which does not resemble my real name in any way.

    However, Facebook requires phone number verification before you complete registration on Facebook. This is the only place where I specified my real phone number to receive their security code.

    Once, I completed the verification. The moment I logged in, I could see Facebook giving me a list of suggestions of people I may know. It was surprising indeed, since this list was extremely accurate. It included people I knew in the past as well my current acquaintances. It makes me rather suspicious.

    The only way I see that Facebook was able to identify the people who may know me or I may know them was using my phone number. So my assumption is:

    • They appear to have a deal with the telecommunication providers in different countries. Once you disclose your phone number, it looks like they get access to the entire list of phone numbers with whom you have corresponded in the past. Then, they do a second level lookup to identify the Facebook profiles of those corresponding phone numbers.

    Also, interestingly, there are some people with whom I may not have ever corresponded with on phone. But of course, Facebook can find them through other people I know and suggest them to me.

    Am I correct that Facebook was able to do all the correlation of people I know in real life using my phone number?

    It would be interesting to see whether they could still correlate it if I use another phone number.

    Did you use the same phone number for your anonymous Facebook profile and your main one?

    @paj28: You cannot reuse a phone number. You cannot register multiple accounts on facebook with the same phone number. Please read this: https://www.facebook.com/help/187931727930637 (If you click on this link, Facebook would be able to see where you came from, so it would be interesting if they actually read this post).

    Frankly IMO this question could be pared down to very little more than "with a brand new account with only a phone number as a personal identifier, how is Facebook able to so accurately suggest people I may know?". The wall of text (literally a screenful of it) adds very little above and beyond that.

    @NeonFlash - so what phone number did you use? Is this a throw-away prepaid number, or a number that you do actively use to communicate with people?

    Edited to remove unnecessary detail and simplify down to the core assumption and question.

    If your account of your account (teehee) is accurate, then we can derive that yes, yes they did.

    @NeonFlash - You haven't told me what phone number you used, but I suspect you did use the same one as on your main profile. When you activated that on your anonymous profile, it removed it from your main profile, but then the two accounts were linked in a way that is not directly visible, but causes friend suggestions.

    I thought that the suggested "people you may know" could potentially be linked to the people that have viewed your profile recently and who are currently not in your friend list. Thoughts??

    Wow, Facebook requires you to go submit to phone verification on new accounts now?

  • executifs

    executifs Correct answer

    7 years ago

    So, yes, they appear to have a deal with the Telecommunication Providers in different Countries.

    Well that's ONE explanation.

    Another one that I like better is simply that they have all their users' contact lists, thanks to their mobile application which no doubt reads everything and sends it back to their headquarters.

    All they have to do after you register with your real phone number is look through all those contact lists, and find the people who possess your number.

    This idea that they may have arrangements with telecom providers seems a little far-fetched to me, in great part because it is simply illegal in many countries to disclose phone records to anyone without a court order.

    This is how i would explain it, too. Seems the most logic explanation to me.

    Agreed - the mobile app explicitly gives Facebook permission to see your contact list.

    Yes, that is an easy way for them to grab the contact list and later perform lookups on it when you register with your Phone Number.

    Yes: unfortunately your contacts have leaked your details to Facebook, probably without telling you; almost certainly without asking.

    Now I understand why the Facebook app on Android randomly tries to read my contacts. Glad I've blocked it (although I'm sure it's too little, too late).

    @TimS. Alas, you can't possibly hope that all those who have your phone number have done the same...

    @NeonFlash Could you check if the list of "people you might know" corresponds with the list of people who might have that (your) phone number in _their_ contact lists?

    Or: use new numbers (e.g. Google Voice, since it's free) A and B with anonymous accounts A and B. Add B's number to A's contacts, install the FB app on A (if it asks, don't scan your contacts for friends), and see the "magic" connection between A and B. (I'm almost sure this'll work)

    Does this mean that somebody I don't know could put a criminals phone number into their mobile phone with my name, and I could be wrongly identified as that criminal?

    @BumblebeeMan I don't see how that makes any sense. It identifies by phone number, not by contact name. Unless you have and use the criminal's phone number. Then it's starting to sound like you're the criminal at that point.

    @BumblebeeMan If someone put your number as a main number and a criminal's number as your cell number, it may or may not be smart enough to link the numbers and suggest all the criminal's friends. Sounds like an interesting experiment

    @BumblebeeMan - No. Per this answer, it goes "This person has your phone number. Let me see if you know them" and suggests them to you.

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Content dated before 7/24/2021 11:53 AM