Setting up more than one verification method. To do so, go to office.com, sign-in and go to your account settings.
Go to “Security & privacy” and then “Additional security verification
Select “Update your phone numbers used for account security” as indicated by the red arrow below.
On this page you can edit your default authentication method, add an alternate phone number (for example your office number that can be called if you lose or forget your cell phone), and/or set up the authentication app on your cell phone
In the future whenever you sign in to your Microsoft account you will sign in with your password and a code sent to your phone