The account says that AT&T's Internet peering traffic, as well as voice traffic, is being intercepted:
AT&T provided National Security Agency eavesdroppers with full access to its customers' phone calls, and shunted its customers' internet traffic to data-mining equipment installed in a secret room in its San Francisco switching center, according to a former AT&T worker cooperating in the Electronic Frontier Foundation's lawsuit against the company.
Mark Klein, a retired AT&T communications technician, submitted an affidavit in support of the EFF's lawsuit this week. That class action lawsuit, filed in federal court in San Francisco last January, alleges that AT&T violated federal and state laws by surreptitiously allowing the government to monitor phone and internet communications of AT&T customers without warrants.
On Wednesday, the EFF asked the court to issue an injunction prohibiting AT&T from continuing the alleged wiretapping, and filed a number of documents under seal, including three AT&T documents that purportedly explain how the wiretapping system works.
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.
This information goes well beyond what had already been determined about AT&T's gigantic call detail record (CDR) database, Daytona, that preserves a record of decades of telephone calls. That database included only the phone numbers and dates and times, not the actual content of the calls. This new information, by contrast, suggests the ability to actually intercept the content of voice calls and Internet data transmission.
"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.