The term itself is vague in nature, but its name would imply that it is responsible for maintaining the link between our dimensions that makes transporting individuals to the facility possible. In my own reality, incidents of accessing alternate dimensions have been recorded but are generally accidental in nature.
My skepticism on the matter is largely associated with the loss of individuals via this technology. While I do not consider such occurrences to be outside the realm of possibility, I also do not consider it likely that the wardens would be forthcoming about any individuals who had left, either by finding their own means to leave or by being returned to their homes, as this would contradict the sentences we are handed upon arrival.