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 have 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 to your calendar to add other people's calendars to your view.
Instructions for Outlook on the web
- Click on the 'App Launcher' in the upper left-hand corner and select 'Calendar'. (Click on All apps and look for if necessary)
- Click on 'import calendar'.
- To add a calendar that belongs to someone in your organization (or a resource calendar), Click 'From Directory'. Enter the calendar name and click add.
- To add a calendar that has been published on the Internet, such as a ShareURL, Click 'From Web'. The Internet calendar must be shared publicly and the URL should end with '.ics'. Enter the calendar name and click 'Import'
Instructions for classic (old) Outlook on the web
- Click on the 'App Launcher' in the upper left-hand corner and select 'Calendar'. (Click on All apps and look for if necessary)
- Within the Navigation Pane, right-click 'Other Calendars' and 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 have entered the name, select 'Open'.
- 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'.
NOTE
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.