AT&T's Room 641A: NSA Interception Facility Revealed by Former Technician

Discovery of Room 641A

Room 641A is a telecommunication interception facility operated by AT&T for the U.S. National Security Agency (NSA) as part of an American mass surveillance program. The facility began operations in 2003, and its purpose was publicly disclosed in 2006 by former AT&T technician Mark Klein.

Facility Details and Capabilities

Located in the SBC Communications building at 611 Folsom Street, San Francisco, Room 641A measures approximately 24 by 48 feet. It houses several racks of equipment, including a Narus STA 6400, a device designed for high-speed interception and analysis of internet communications. The facility is connected to fiber optic trunks carrying internet backbone traffic via beam splitters. According to J. Scott Marcus, a former CTO for GTE and FCC adviser, the room has access to all internet traffic passing through the building, enabling surveillance and analysis of internet content on a massive scale, including both overseas and domestic traffic.

Legal Challenges and Public Attention

Following Klein's revelation, the Electronic Frontier Foundation (EFF) filed a class-action lawsuit, Hepting v. AT&T, on January 31, 2006. The lawsuit accused AT&T of violating privacy laws by collaborating with the NSA in an illegal program to wiretap and data-mine American communications. A federal judge denied motions to dismiss the case in July 2006, allowing it to proceed. However, the case was dismissed on December 29, 2011, based on a retroactive grant. Room 641A and the controversies surrounding it were also featured in documentary programs on PBS, including Frontline and Nova.