1. Sign in to Microsoft 365 with your work or school account with your password like you normally do. After you choose Sign in, you'll be prompted for more information.

    A dialog box telling you that more information is required to complete your sign-in
  2. Choose Next.
  3. If you would rather use SMS messages sent to your phone instead, select I want to set up a different method. Microsoft 365 will ask for your mobile number, then send you an SMS message containing a 6-digit code to verify your device.