Managing Microsoft 365 MFA Settings
Navigate to https://mysignins.microsoft.com/security-info
The default authentication method is to use the free Microsoft Authenticator app. If you have it installed on your mobile device, select Next and follow the prompts to add this account. If you don't have it installed there is a link provided to download it.
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.
Tip: For a faster, and more secure, experience we recommend using an authenticator app rather than SMS verification.