There are 3 teleporters located around the map that will take you back to the mainframe in the courtyard where you start the game.
After linking them by starting a 30 second clock for you to run back to the mainframe and press X, the teleporters cost 1500 each time. Therefore you and your teammates (if there are any) will need to spend at most 12000 to get this achievement.
Teleporters will also give you a free teleport when they are first connected, so you can get 3 free teleports in if you are the one to initiate all the links.
You can use any teleporter you like, and do not have to have all 3 connected, although it isn't much trouble to do so.