http://blogs.technet.com/b/office_resource_kit/archive/2011/04/21/office-communicator-2005-is-not-supported-with-outlook-2010.aspxHi there, We've heard that there has been some questions on which versions of Microsoft Office Communicator are supported with Outlook 2010. The supported versions are Office Communicator 2007 and later versions (including OC 2007 R2 and Lync 2010). Officeen-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)