The 12th System was the name given to the process of where humans were taken and injected with nanobot technology in order to mold them into becoming Silencers. Vosch developed this method in order to create new sleeper cell agents among the humans. The only successful person seen to undergo the 12th System and live was Ringer. She was classified as a success.
Vosch spun a tale to the recruits of Camp Haven that they had managed to capture alien technology from the others in the form of programmable nanobots. Using them, it was possible to take Infesteds and cleaning them out of the alien presence and make them human again. It was to be known as The 12th System. However, what it really was was a way to enhance humans and turn them into Silencers.
Vosch hadn't had a success with this procedure yet and decided to try it on Ringer whom they had captured. Using Teacup's life as his leverage, he had Ringer comply to the procedure.