Set up your text options in the Outlook Web App
Go to Mail Options in the Outlook Web App (When logged into portal.office.com, click the gear in the upper right-hand corner and then choose ‘Mail’ under My app settings). Under General, choose Text Messaging. The next screen you get will depend on whether not you've set up text messaging alerts before. If you haven't, it will look like this:
Choose “Set Up Text Messaging” (or “Edit Text Messaging Settings” if you have a different screen). You’ll choose your wireless carrier, enter in your phone number, and then get a passcode to enter to verify your identity.
Set up your Calendar Notifications
After you’ve verified your phone number, click “Set Up Calendar Notifications” (or in the Settings sidebar, click “Notifications” under Calendar:
Check these boxes:
And Click Save. You're done!