Many Facebook users receive information displayed at the top of the Facebook page.

It says: “Add your phone number to protect your account and more.” Some users are confused about what this information is all about. Some believe that Facebook wants the phone number for advertising purposes. We have taken a closer look at this and would like to show in this report what it is all about.

This information is about:

There is a link behind the word “more” (at the end of the information). If you click on this, you might assume that you will get further information about why you have to provide your telephone number. http://www.facebook.com/about/privacy/your-info

Unfortunately, that's not the case, because you're just redirected to the Facebook "Data Usage Guidelines → Information we receive about you" and it doesn't really say why you should provide your phone number or why this gives you more protection.

The only paragraph where “telephone number” appears is this:

“Registration data

When you register with Facebook, you will be required to provide certain information such as your name, email address, birthday and gender. In some cases, you may be able to register using other information (such as your phone number)”

But it still doesn't say what you're being protected from.

Then why does Facebook write, “…to protect your account”?

There are several “security mechanisms” on Facebook.

Facebook itself writes:

“If you ever have problems with your account, you can use this information to reset your password and log in again. It’s also easier for others to stay in touch with you.”

What does that mean?

In addition to your contact email address (there can be more than one, you can now also include your mobile phone number in your security question , for example to retrieve a forgotten password!

Facebook itself describes the topic of “mobile phone numbers” like this:

Why does Facebook become more accessible to me when I add a mobile number to my account?

Some of our security checkpoints may be difficult to pass with assistive technology. By providing a mobile phone number in your Facebook account, you have an alternative to verifying your account in case you need to go through one of these checkpoints.

You can add a cell phone number on your cell phone settings We are working to resolve the issue and apologize for any inconvenience this may cause.

or

I do not have access to my account and will provide confirmation of my email address or mobile number.

New users must verify their email address or mobile phone number to use Facebook. Some users are allowed to access Facebook for a short time, but will be blocked if they do not verify their accounts.

Verifying your account helps us ensure that you are a real person. This helps ensure the security of the website and keeps it free of spam.

If you can't verify your account and have lost access to it, let us know.

or

Why do I need to prove my identity using my phone number?

This is a security measure that helps us confirm that you are a real person who only has a Facebook account. To prove your identity, all you need to do is follow the instructions on the page to add your mobile number. Once we can verify your identity, you will be able to access your Facebook account again. We will not contact you by telephone without your consent.

Note: Having multiple accounts violates Facebook's Terms of Service . If you have multiple accounts, your additional accounts will be deactivated. Select the account you want to keep and verify your identity using that account.

or

Why am I seeing an ad on my homepage telling me to increase the security of my account? Does this really come from Facebook?

Yes. This ad is from Facebook. We want to make sure you don't get locked out of your account. That's why we've provided a tool to help you check your account security and update your information.

You should add additional contact information to your account (such as another email address or a mobile phone number) so that we can contact you if you are unable to access your main email address. We also recommend that you provide a security question for your account if you have not already done so. Note that we may ask you to re-enter your password if you update your sensitive account information. Get started now .

So what does this information mean for Facebook users?

If you want to add another level of security , you can provide your cell phone number, but you don't have to.

If you install these security levels but you don't want your mobile number to be seen by others, then you should set your number to “Only me”.

You will find this setting in your “INFO”: