Add backup options for 2FA/MFA

Add Your Phone Number

1. Visit https://mysignins.microsoft.com/security-info
2. Select +Add sign-in method
   
3. Choose Alternate Phone
   
4. Select Add
5. Enter your phone number and select Next
   
6. You will receive a call to confirm the number you entered is correct

Add a Secondary Device or Secondary Number 

Smart phone: Adding Microsoft Authenticator app

Cell Phone (Non-smart phone)

Landline or VoIP Phone

YubiKey Security Key