By default the function to publish your calendar to the internet is turned off / greyed out.
To enable this function log in to the Exchange server and open the Exchange management shell.
There are different options for this policy.
For sharing only the free/busy data you have to type:
New-SharingPolicy -Name “Calendar Sharing Policy” -Domains “anonymous:calendarsharingfreebusysimple”
If you want to have the ability to share the full calendar with all details you have to type:
New-SharingPolicy -Name “Calendar Sharing Policy” -Domains “anonymous:CalendarSharingFreeBusyReviewer”
Now you have to apply the sharing policy to a user:
set-mailbox email@example.com -SharingPolicy “Calendar Sharing Policy”
When you log in to the OWA go to:
Calendar -> Share -> publish this calendar to internet
Choose the settings you like and click Save.
You will now see 2 URL’s.
1 is for viewing the calendar in a webbrowser, the other is for adding the calendar to Outlook.
To add the calendar to Outlook copy the link with .ics as extension.
Go to Oulook and go to: Calendar -> Open calendar -> from internet and paste the URL.
You have now enabled internet calendar sharing and added it to your Outlook!