I'm trying to build a contact list based on a available contacts. However, how do I find a contact's availability? I've synced my contacts list to Outlook, however looking through the available columns there doesn't seem to be anything for whether available status? What is the best approach, is it necessary to check each contacts calendar?
You can use the Exchange Web Service API to get contact availability information. Details and samples can be found here: http://msdn.microsoft.com/en-us/library/exchange/jj220501(v=exchg.80).aspx#AvailabilitySection