In Main/COnfiguration/Chat and video  you can set up a parameter called "Room limit for user", this parameter specify how many room can be programmed in the same time by a single teacher, this is useful to disallow any kind of "room monopolisation"

After this you can setup access codes for one of the 2 supported systems (DimDim, Teleskill).

Room activation can be scheduled in a classroom area called Videoconference, when active teacher and students can enter in the virtual classroom already identified with the name and surname used in Docebo.