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?