So, who are they? (SPOILERS!!!)
And by they, I mean the callers' bosses.
My guess would be aliens since some hints point to that conclusion (there's an experiment involving humans, only thousands of humans survive, force fields are probably alien tech, and there was clearly a war, since the girl claims that her husband died in it.
The alternatives are Skynet, of course, since this is clearly inspired by Terminator (the Callers being the equivalent of infiltrator terminators) and this could be how the Terminators learn about human behavior) or secret government experiment (after a civil war fascist government came into power and is trying to brainwash the children of its opponents), although this theory is a real stretch.
Any other theories, or do you agree with one of these?