According to a statement released by Klein's attorney, an NSA agent showed up at the San Francisco switching center in 2002 to interview a management-level technician for a special job. In January 2003, Klein observed a new room being built adjacent to the room housing AT&T's #4ESS switching equipment, which is responsible for routing long distance and international calls.
"I learned that the person whom the NSA interviewed for the secret job was the person working to install equipment in this room," Klein wrote. "The regular technician work force was not allowed in the room."
Klein's job eventually included connecting internet circuits to a splitting cabinet that led to the secret room. During the course of that work, he learned from a co-worker that similar cabinets were being installed in other cities, including Seattle, San Jose, Los Angeles and San Diego.
"While doing my job, I learned that fiber optic cables from the secret room were tapping into the Worldnet (AT&T's internet service) circuits by splitting off a portion of the light signal," Klein wrote.
The split circuits included traffic from peering links connecting to other internet backbone providers, meaning that AT&T was also diverting traffic routed from its network to or from other domestic and international providers, according to Klein's statement.
The secret room also included data-mining equipment called a Narus STA 6400, "known to be used particularly by government intelligence agencies because of its ability to sift through large amounts of data looking for preprogrammed targets," according to Klein's statement.
Narus, whose website touts AT&T as a client, sells software to help internet service providers and telecoms monitor and manage their networks, look for intrusions, and wiretap phone calls as mandated by federal law.
