http://blogs.technet.com/uc/archive/2007/04/30/ocs-2007-additional-federation-security-features.aspxIn LCS2005 SP1, two new federation models were introduced; the ability to federate with the three big public IM providers AOL, MSN &amp; Yahoo! and Enhanced federation by which peer enterprises are discovered via DNS SRV. Further, enhanced federationen-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.technet.com/uc/archive/2007/04/30/ocs-2007-additional-federation-security-features.aspx#2151526Thu, 11 Oct 2007 09:56:01 GMTd5e57398-b9ef-4490-9955-07cbb4e4a80d:2151526Johann's Unified Communications<p>Microsoft Office Communicator Mobile is a Unified Communications client for Microsoft Office Communications</p>