Cross Org Availability using Federation Trust and Organization Relationship

Organizations often need to share availability (aka Free/Busy) information with other Exchange organizations. Depending on the version of Exchange Server you're on, there are different ways to do this. Let's take a look at three common scenarios and go through the exact steps required in order to achieve sharing of availability information between two on-premises Exchange organizations.


  1. Scenario 1: Both organizations running Exchange 2010 SP1
  2. Scenario 2: One (or both) organizations running a mix of both Exchange 2007 and Exchange 2010 SP1
  3. Scenario 3: One (or both) organizations running a mix of Exchange 2003, Exchange 2007 and Exchange 2010 SP1

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