I just installed Lync 2013 in my domain. I did have LCS 2005, but I deactivated all the servers and removed it from my domain.
in ADUC it is still showing a sip address for my active users. When I go to the Lync control panel and try and search for a user’s, it is only showing users that don't have a sip address.
It seems that users that were active on the LCS 2005 user are not showing up when I search to enable them.