We have acquired a new entity with their own AD/Exchange environment. Until they fully join our domain, we need to sync their exchange calendars or minimally free/busy for users. All users in the acquisition have a new account in our organization.
We have considered a number of options including CalDAV, but nothing seems to meet our needs.
Even a client solutions to update the NEW server with the free/busy would be workable.
Would the Exchange Replication Service be suitable for you? Nice install\config guide. There's another guide with screen shots if you prefer