When there is an error in the voip configuration, the saros communication preferences should be shown to enable the user to fix the problem.
Right now there is just a dialog, that says that there is an error, but it doesnt tell the user how to fix it.
Suggestion: integrate a button "open comm prefs" in that dialog.
Feel free to fix this, The class your are looking for is
de.fu_berlin.inf.dpp.communication.audio.AudioServiceManager
Improvement, not a bug. (Seems I cannot move the tickets between the trackers anymore). As this feature is disabled by default it should not matter any way because most users will never see this error dialog.