Room 641A - Wikipedia

Room 641A is a telecommunication interception facility at an AT&T site in San Francisco, operated for the U.S. National Security Agency as part of a mass surveillance program that began in 2003 and was revealed by AT&T technician Mark Klein in 2006. The room contains a Narus STA 6400 device and is fed by fiber optic lines from beam splitters on Internet backbone trunks. According to J. Scott Marcus, a former GTE CTO and FCC adviser, it has access to all Internet traffic passing through the building. The Electronic Frontier Foundation's Hepting v. AT&T lawsuit was dismissed in 2011 after Congress granted retroactive immunity, and a 2019 ruling in Jewel v. NSA found Klein could not establish the room's content, function, or purpose from his own knowledge.