Mark Klein, an AT&T technician for 22 years, discovered Room 641A at AT&T's San Francisco facility — a secret room where optical splitters created exact copies of all internet traffic passing through AT&T's backbone and redirected it to the NSA. The room contained a Narus STA 6400, capable of intercepting and analyzing internet communications at very high speeds. Klein went public in 2006 after reading about Bush's warrantless wiretapping program. The EFF filed Hepting v. AT&T, but Congress passed retroactive immunity for telecoms in 2008.