@nologin: in 2006, former AT&T technician Mark Klein discovered a door with no handle labeled "641A" in an AT&T data center in San Francisco. This secure room, known internally as the SG3 Secure Room, housed a fiber optic splitter designed by AT&T & the NSA to intercept and analyze overseas and domestic internet communications at high speeds. Room 641A had access to all internet traffic passing through the building, and therefore "the capability to enable surveillance and analysis of internet content on a massive scale, including both overseas and purely domestic traffic." Klein claims he was told that similar black rooms are operated at other facilities around the country.