By adding security information to your Microsoft account, you'll be verified at sign-in with your email and phone information.
1. Sign in to your Microsoft account. [Link]
2. Select Security > Advanced security options.
3. Under 'Ways to prove who you are,' select 'Add a new way to sign in or verify' or turn on 'Two-step verification.'
For more information on security settings, please check below on the Xbox website.
[Go to Xbox FAQ]