Hi All :

      Lync Server 2013 CU (KB 2809243)  has been released at Jan.8 2014.  You can download this CU from this link : http://www.microsoft.com/en-us/download/details.aspx?id=36820

      The update process is very simple. For the best practice, you can refer this flowchart :  

       

     Now I will to show this process.

     Logon to the Lync Server Frontend server for enterprise edition or standard edition. Open the Powershell cmdlet , run Get-CsPoolUpgradeReadinessState , If the State value of the pool is Busy, wait for 10 minutes, and then try to run the Get-CsPoolUpgradeReadinessState cmdlet again. If you see Busy for at least three consecutive times after you wait 10 minutes in between each attempt, or if you see any result of InsufficientActiveFrontEnds for the State value of the pool, there is an issue with the pool.

     Stop new connections to the frontend server by using the Stop-CsWindowsServers cmdlet and run Get-CsPoolUpgradeReadinessState again

     Make sure the State is Ready, go to the update phase. Open the Lync Server 2013 Cumulative Update Installer,  you will to see the updates list :

    Click Install Updates will start automatic installing process

       Wait some minutes, the updates install completed

    Then use Start CsWindowsServices cmdlet to starting all services. Logon to the Lync Server 2013 Control Panel, you can see the version is 5.0.8308.556:

   Now the update is completed. For more information, please check the KB 2809243 : http://support.microsoft.com/kb/2809243/en-us

  

   Enjoy!

   Justin Gao

   Microsoft (China)