When you access your account, we want to make sure it’s you who is making any changes. We’ll send a one-time security code to the phone number or email address you’ve provided. When you enter the code we sent you, we’ll know it’s really you.
For this reason, it's important that you use a real phone number and email address for your alternate contact info. We'll never use this info to spam you or for any marketing purposes—it's only to verify your identity if there's ever a problem with your account.
If you change your account info frequently, you might want to set up a trusted device (like the PC you sign in to most frequently), so that you don't need to enter a security code every time you make a change. For more info, see What is a trusted device?
Or, if you sign in frequently on devices that aren't trusted (like a public or shared PC), we recommend that you set up two-step verification to keep your account more secure. Two-step verification will always prompt you for a security code in addition to your password. If you decide to turn on two-step verification, it's especially important that your alternate contact info is valid, because you'll need it to get your security codes. For more info, see Two-step verification: FAQ.
To get started with adding account security info, follow these steps:
Sign in to your Microsoft account.
On your account page, under Password and security info, tap or click Edit security info.
If you're prompted to enter a security code, check your alternate email or phone for the code from the Microsoft account team.