Adding exchange room calendars to iPad

Solved.

The vast majority of this is PowerShell script. (Start > Powershell Modules)

First of all you need to set up the web proxy: (to be honest, I skipped this bit as the iPad in question will never leave the building and an external URL isn't required)

To check settings:

Get-ExchangeServer |fl

To set setting:

Set-ExchangeServer -Identity "MAIL01" -InternetWebProxy "<Webproxy URL>"

Next, the virtual calendar directory needs to be set to shared:

To check settings:

get-owavirtualdirectory |fl

To set setting:

Set-OwaVirtualDirectory -Identity "CAS01" -ExternalUrl "<URL for the CAS01>" -CalendarPublishingEnabled $true

Next, in the Exchange Management Console, go into Organisation Configuration > Mailbox and create a new policy. Set the domain to Anonymous (this is the bit that threw me as I assumed using the * wildcard for domain would do what I was after but no!) and the sharing settings to Calendar sharing with free/busy information and whatever level of access you want to give people.

Assign the new policy to the resource mailbox:

Set-Mailbox -Identity <mailbox alias> -SharingPolicy "<sharing policy>"

Enable publishing on the calendar:

Set-MailboxCalendarFolder -Identity <mailbox alias>:\Calendar -detaillevel fulldetails -publishenabled $true -reseturl

At this point you can see the mailbox's url (both as an html to view and an ics to subscribe to) by running:

get-mailboxcalendarfolder -Identity <mailbox alias>:\calendar

At this point, I believe it's sorted. As an added extra though I figured out how to send an email from the calendar account. First log into OWA as you would normally (note, your account needs to have a level of control of the room account. I had mine set to full control and send as), then change the url to https://<OWA url>/owa/<full email address of room>/#

Apologies for any lack of detail or terminology. Hope it all makes sense.