Exchange 2010 Sharing a calendar using OWA prompts for Credentials

Question

Hi,
We have a mixed Exchange 2003/Exchange 2010 environment while we migrate our mailboxes over to Exchange 2010.
We use code that is used to connect to meeting room calendars still on Exchange 2003and then display the information on big tv screen at the entrance to the building.
An example of the code is:
R1calURL = "http://www.msexchange.org/articles-tutorials/exchange-server-2010/management-administration/managing-internet-calendar-sharing-exchange-server-2010-service-pack-1-part1.html to
try and get it working.
The code then gets various other pieces of information from the calendar which is used to display the correct information.
I have a couple of questions:
1) Is this method still valid or should we be using a different way of acheiving this (EWS or Internet Calendar Sharing?)
2) We use forms based authentication for OWA.  I have had a look at Internet Calendar Sharing but when I enter the URL for the shared mailbox I am always being asked to enter credentials.  I have configured the mailbox I am connecting to so default
has reviewer and anonymous has reviewer permissions.  I have also configured the OWA external URL the same as the Internal URL and created a new anonymous sharing policy in the EMC and applied this to the shared mailbox.  I used the following link
http://www.msexchange.org/articles-tutorials/exchange-server-2010/management-administration/managing-internet-calendar-sharing-exchange-server-2010-service-pack-1-part1.html to try and get it working.
Any help would be greatly appreciated.
Matt

Answer 1

Hi Matt,
If the shared calendar is opened from OWA directly from a URL, please configure the Outlook Web App virtual directory to use Integrated Windows authentication. Integrated Windows authentication lets users who've already logged on by using
their Active Directory account use Outlook Web App without having to enter their credentials again. For more information about it, please refer to:
http://technet.microsoft.com/en-us/library/bb232199(v=exchg.141).aspx
To configure it, please do the following steps:
1. Open EMC, expand Microsoft Exchange On-Premises (<ServerName>).
2. Expand Server Configuration, and click on
Client Access.
3. Select the desired Client Access server on the right panel, and double click on
owa (Default Web Site) on the Outlook Web App tab.
4. In Authentication tab, select Use one or more standard authentication methods and check Integrated Windows authentication.
5. Click Apply.
Please note the warning to restart IIS service and change the corresponding configuration for ECP virtual directory in the same web site.
Regards,
Winnie Liang
TechNet Community Support