Joining an already running room

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I am trying to create a simple game, that will consist of up to 50 players in a single room. I've downloaded and configured the server, but all the examples included with the unity bundle only spawn the scene with the players from the start. There doesn't seem to be the ability to let people join an already created room.

Is it possible in PUN to allow people to join and leave a room, without restarting the scene or launching a new scene?