Facebook mobile app is often asking about my phone number for registration. It shows a screen saying that "Keep your account secure and keep using it securely" and "We are trying to help you to secure your account .... register your phone number etc."

And the suspicious side of this is that, the phone number input is filled already as you see in the screenshot. Each time a different phone number appears in this field.

Last time when I saw this screen, it was showing my very old home-phone number, even before Facebook. I have never registered my home-phone number for any website or application, I'm sure about it.

I asked Facebook about this, but no reply received yet. Has anybody ever encountered something like this before? Where does Facebook take this phone numbers? Any idea?

enter image description here

2 Answers 2


If any of your friends have shared their contact details with Facebook, they may well have picked it up from there. It's buried in the terms and conditions that they have on account creation, so it's very easy to miss...

  • Let's say what you've said is true, but there is a still ethical issue here. This means Facebook can expose anyone's phone number to anybody on their related network. Anyway, this can not be in EULA. It seems to me there is an important bug.
    – Erce Tilav
    Commented Jan 4, 2017 at 13:56
  • Here's the link to their privacy information: facebook.com/about/privacy - the section you need to look at is "Things others do and information they provide." If someone else imports their contact database, and you're in that, Facebook can (and does) link that data to you, although they don't show it to anyone else without your permission, in theory.
    – Matthew
    Commented Jan 4, 2017 at 13:58
  • 2
    I'd agree that there was an ethical issue, by the way, but that would be off topic here...
    – Matthew
    Commented Jan 4, 2017 at 14:00

Even if you don't share your information with Facebook for whatever reason, your friends and family might.

With all the aggregated information they have gathered it's not that hard to fill in the blanks.

I don't think you're invisible to Facebook even if you don't have an account, it's just that the information they already have on you should not be published or used by them, as you haven't signed any EULA.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .