Or you can just make your own system for authentication for getting into the server... so the servers would show up on the list but when someone tried to join it just told them there current location was somewhere else. Whipped up a quick map about how the servers could work in relativity to the zones,
(these are actually plans for a project of mine)

The purple areas are the parts that the servers cover, with the purple one being the most powerful, and blue and maroon be on slower computers.
(purple would have to be the fasted because it contains the main city, a zone, and the PVP area.)
There could be things like, inns and when a player leaves the game, (like, away from the whole thing) it checks which inn they are closest too and sets their location there, or it actually sets their location to where they are. It would be ideal to have the code that allows access to the servers to be serverside, so that people cannot hack into the servers with the client code they DLed.