Using Microsoft Authenticator App (iOS & Android)
You will be prompted to authenticate your sign in every 7 days and when you sign in to a new device. For example, when you login to Outlook on your computer, it will provide you with a randomly generated two-digit code shown below:
Then it will send you a notification on your phone to allow the sign in. Click on the notification...
It then will prompt you to enter the two-digit code as shown below...
Please note: If you're authenticating the sign in on the same device you have the authenticator app installed, it will only show the two digit number for a second then block it to enter it. However, you can click on "I can't see the number" in the screenshot shown below and it will disappear for 3 seconds for you to see the number then reappear again to enter it.
Passwordless Authentication
With the Microsoft Authenticator, you can set up Passwordless Authentication (optional). With passwordless authentication, you can access a trusted device without having to enter a password. Only the two digit number is required. See Setup Passwordless Authentication
Authenticate even when your phone doesn't have internet access via mobile data or WiFi
Follow the yellow highlights in the screenshots below in order after you're asked to authenticate. You will use the 6-digit code inside the app. It will not send you a notification as usual. Note, if you have passwordless sign-in enabled, click on Use your password instead and enter the password and you'll be led to the first screenshot below.
What to Expect/How Many Times Do I Need To Authenticate
-On each device, MFA will prompt you to authenticate once a week when using installed apps such as Word, Excel, PowerPoint, and Outlook (they don't ask you to authenticate on each of those apps)
-The Teams and OneDrive will also require separate authentications once a week on the same device.
This means you could potentially encounter up to two or possibly three authentication prompts per week on the same device.
To identify if Outlook or Office apps need authentication, simply look for an exclamation mark next to your name on the top-right of the app.
Additionally, if you access these apps on different devices or a new device, you'll be asked to authenticate again as listed above.
For Office 365 activity in a web browser, you will be asked to authenticate every time you sign in. This is because web browsers don't store token keys. If you frequently use the browser for login, you'll usually met with the message "Stay signed in?", check the box that states Don't show this again then click Yes to streamline the process. Note that this option does not work in incognito/private mode of the browser.
-If Teams needs to be authenticated, it must be authenticated once a week on the same device for the locally installed Teams app; otherwise, it may miss calls.