Outlook Web App allows you to add other calendars to your calendar view. Depending on the permission levels you have been granted, you will be able to act on these permissions (Free/busy, Read, Write, etc.).
If you've received an invitation to share someone else's calendar, you can select the link in the invitation to add their calendar to your calendar view.
You can also go your Calendar to add other people's calendars to your view.
- Open the app launcher tool in the top left of your Outlook Web App window as shown below.
- Select calendar from the list of available apps.
- Within the Navigation Pane, right-click Other calendars. Or, touch and hold if you're using a touchscreen device.
- Select Open calendar.
- To add a calendar that belongs to someone in your organization (or a resource calendar), enter their name in From Directory. This box works just like the To box on a new email message. After you've entered the name, select Open to search for and add the calendar.
- To add a calendar that has been published on the internet, such as a ShareURL, enter the URL in the Internet calendar box, and then select Open. The Internet calendar must be shared publicly and the URL should end with .ics.
After you've added the calendar, you can left-click on that calendar and interact with the events per the permissions you have been granted.
IMPORTANT: If you receive a URL from an Office 365 user and want to open up the URL via a web-browser, you must change 'HTTP' to 'HTTPS' for the URL to work properly.