Washington – Armed with details of billions of telephone calls, the National Security Agency used phone records linked to the Sept. 11, 2001, attacks to create a template of how phone activity among terrorists looks, say current and former intelligence officials who were briefed about the program.
The template, the officials say, was created from a secret database of phone call records collected by the spy agency. It has been used since 9/11 to identify calling patterns that indicate possible terrorist activity.
Among the patterns examined: flurries of calls to U.S. numbers placed immediately after the domestic caller received a call from Pakistan or Afghanistan, the sources say.
USA Today disclosed this month that the NSA secretly collected call records of tens of millions of Americans with the help of three companies: AT&T, Verizon and BellSouth.
The call records include information on calls made before the Sept. 11 attacks.
Verizon and BellSouth released statements last week denying they had contracts with the NSA to provide the call information.
A Verizon spokesman said the company’s statement did not include MCI, the long-distance company that Verizon acquired in January.
The “call-detail records” are the electronic information that is logged automatically each time a call is initiated.
For more than 20 years, local and long-distance companies have used call-detail records to figure out how much to charge each other for handling calls and to determine problems with equipment.
In addition to the number from which a call is made, the detail records are packed with information. Also included: the number called; the route a call took to reach its final destination; the time, date and place where a call started and ended; and the duration of the call.
The records also note whether the call was placed from a cellphone or from a traditional “land line.”
“They see everything,” says Sergio Nirenberg, director of systems engineering at Science Applications International Corp., a Fortune 500 research and engineering company that works with the federal government. Nirenberg said he does not have direct knowledge of the NSA database.
Using computer programs, the NSA searches through the database looking for suspicious calling patterns, the officials say.
Because of the size of the database, virtually all the analysis is done by computer.
