Last year we moved on to a Cisco based telephony infrastructure and installed Cisco Jabber on our client machines. We deployed Cisco Jabber via Microsoft group policies using the standard MSI file provided by Cisco. The deployment was successful however we ended up getting a lot of complaints from the users about not being able to login.
After some troubleshooting together with support, we established that the GPO deployed Jabber application was trying to authenticate against a WebEx Connect server on the cloud rather than the Unified Communication server based locally in the LAN. Since there was no WebEx Messenger subscription, the login process was failing. The solution was to customise the MSI file and prevent the installed Jabber application from trying to authenticate against a Webex Connect server.