has something changed with Jabber 11.8?
With 11.7 installed as follows, everything works fine
msiexec.exe /i CiscoJabberSetup.msi /quiet CLEAR=1 UPN_DISCOVERY_ENABLED=false
With 11.8 installed on the same machine in exactly the same way, contacts, and your screen name do not "resolve" so you only see their email address and not their name.