Skype for Business Server 2015 is available now, along with a new set of demands to install it right on your Windows Server.
Here are the recommendations for each Windows version:
Windows Server 2008R2: Microsoft recommends that you only install Skype for Business Server 2015 on Windows Server 2012 or 2012R2. However, if you’re in-place upgrading from an existing installation of Lync 2013, you might like to use your existing Windows 2008R2 server. The following procedure assumes you already have Lync 2013 installed on your system, so all prerequisites should already be installed. Continue reading