Presencia desconocida/Presence unknown Lync 2013/Skype for bussines

PROBLEM:
contacts at Lync/Skype clients shows "presence unknown"


SOLUTION:

delete %UserProfile%\AppData\Local\Microsoft\Office\15.0\Lync in the computer client.

(Create a GPO to apply all Organization computers)

references: http://blog.insidelync.com/2013/09/lync-2013-presence-issues/