The option to add a phone number is missing. I need to know how to add it when this option isn't there

If Add phone number is absent from your personal Microsoft account, you cannot manually restore it; Microsoft is phasing out SMS authentication and now directs affected accounts to use a recovery email, Microsoft Authenticator, or a passkey instead.^1^

Add another verification method

1. Open the Microsoft account Security page:
   https://account.microsoft.com/security
2. Sign in and select Manage how I sign in.
3. Select Add a new way to sign in or verify.
4. Choose one of the options displayed:
   • Email address — add an address you can access for verification and recovery.
   • Microsoft Authenticator — approve sign-ins through the app, including when the verification device is offline.
   • Passkey — sign in using your device’s face recognition, fingerprint, or PIN.
5. Complete the displayed verification process.

Microsoft specifically notes that Add a new phone number may not be available and that only these alternatives may appear.^2^

For resilience, add more than one available method—for example, a recovery email plus a passkey or Authenticator. Do not remove your only working verification method before the replacement is active.

If this is a work or school account

Phone availability is controlled by the organization. Go to My Account → Security info → Add method. If Phone is not listed, the organization may not permit it; contact the account administrator.^3^

Windows 11 settings, browser changes, or restarting the PC will not add an option that the account-security page does not offer.

References

1. Microsoft to stop sending SMS codes for personal accounts
2. Microsoft account security info & verification codes | Microsoft Support
3. Set up a phone call as your verification method | Microsoft Support