>Probably I have accepted all your terms and conditions
Yes, you did accept their terms and conditions. How does Facebook not have your mobile number when you're using their phone app? That thing knows more about your phone than you do (try reading its T&C).
I ignored the terrible ESL grammar, and powered through the "nothing to hide" fallacy, but in the end I'm so frustrated with the technological naivety of the author that his main point is lost. Apologies for being brash, Nitin, but you have to expect some scrutiny when you post on HN; this is a tech forum.
Though I don't doubt that Facebook would play on what's said in my first sentence, the fact that the person who's bringing the issue up seems to have been in a cave since 2013, and is only working with a control of 1, I'm going to write this off as user error until someone savvy verifies the claim.