The same all symptoms accurs in our win 10 PCs, an enterprise edition.
I found that this issue related to the snnheiser dll somehow.
when I block this dll - I don't know why -
1. Jabber stop the connection to the phone by medianet plugin
2. the the call control to the deskphone works good.
3. the camera works under Options->Video..
I mete with this on Jabber 11.9(2), 11.9(3) and now with the latest release 12.0(1)
