This post describes how to configure Exchange 2013 OWA to have IM integration to Lync 2013. Here I would like to give some troubleshooting tips in case you can't get the integration to work.
OwaVirtualDirectory and OwaMailboxPolicy
Lync 2013 Topology
Logfile and tracing
Great article. According to MS you need UCMA installed on the MBX which of course i'm using since it's a requirement for Exchange 2013. But the registry key "InstantMessaging" didn't exist at the below location so I re-installed UCMA. Now OWA doesn't even
try and log into IM, when I click on Sign into IM nothing happens. Also no log files are being produced on the MBX. Rebooting the MBX doesn't achieve anything. Any thoughts?
Another item to check is the Lync Trusted Application/Pool, I though I made one referencing my new owa site but had not :)