Providing Phone number for online services (gmail, facebook and so on)

What information can be found with this? Gmail seems to be asking for my phone number a lot when creating new gmail accounts. A lot of companies also ask for your phone number for 2FA authentication.

For anonymity from these information selling companies, I provide fictitious details when making my account. However, I am forced to use a real number that is in constant use to verify them. Just how much of my usage information is traceable back to my …

2fa accounts anonymity ask asking authentication can companies facebook found gmail information lot making online services phone phone number privacy selling services