Hybrid Cloud : On-Premise Lync with Exchange Online

One of the unique capabilities of Office365 is the ability to deliver a seamless hybrid cloud, so moving to a cloud delivery model does not need to be an "everything on the browser" technology ultimatum. Check out this great post by Dr Rez on how we enable Hybrid Cloud

https://blogs.technet.com/b/nexthop/archive/2011/06/28/configuring-on-premises-lync-server-2010-integration-with-exchange-online.aspx