What is Room 641A?

Room 641A is the physical proof that the US government conducts mass domestic surveillance — not through legal requests to companies, but by literally splitting the internet's backbone cables and copying everything.

What It Is

Room 641A is a windowless, secure room on the 6th floor of AT&T's Folsom Street switching facility in San Francisco. Inside:

• Fiber optic splitters (made by Narus, a Boeing subsidiary) duplicate all internet traffic passing through AT&T's network
• The copied data is routed to the NSA for analysis
• The room handles traffic for AT&T's WorldNet customers and peering links with other ISPs
• All traffic is copied — not just targeted communications

How It Was Revealed

Mark Klein, an AT&T technician for 22 years, observed the room's construction and operation in 2003. He:

1. Saw NSA personnel supervising installation
2. Reviewed internal AT&T documents describing the setup
3. Understood that the fiber optic splitters copied 100% of traffic — not filtered, not targeted
4. Provided documents and testimony to the Electronic Frontier Foundation (EFF) in 2006
5. EFF filed the landmark case Hepting v. AT&T

The Cover-Up

• The government invoked state secrets privilege to have the case dismissed
• Congress passed the FISA Amendments Act of 2008, granting retroactive immunity to telecom companies that participated in warrantless surveillance
• AT&T faced no consequences
• Similar rooms are believed to exist at AT&T facilities in Seattle, San Jose, Los Angeles, San Diego, Atlanta, and other cities

Why It Still Matters

Room 641A proved that mass surveillance isn't theoretical — it's physical infrastructure bolted to the backbone of the internet. The legal framework that enabled it (Section 702 FISA, Executive Order 12333) is still in effect, and the surveillance has only expanded since 2006.