The device that collects the packets is paired with an Intel-based "logic" server that runs Red Hat Linux and analyzes packets in real-time for pre-configured targets such as IP addresses or "voice prints," he said. It also can check for anomalous patterns..

Determining what patterns to scan for is done separately, typically by using data mining and business intelligence tools to analyze information stored in a data warehouse.

Stephen Brobst, chief technology officer at Teradata in Dayton, Ohio, declined to comment on whether the NSA is using the NCR Corp. division's data warehousing software. But he acknowledged that Teradata's technology is popular with telecom carriers and network services providers for storing and analyzing the massive volumes of call data records and network traffic information they collect.

For instance, Brobst said that AT&T's Daytona data warehouse, which it built in-house partially using Teradata technology, stores 1.88 trillion call records comprising more than 312TB of data.

Richard Winter, president of Winter Corp., a Waltham, Mass.-based consulting firm that produces an annual report on the largest databases being used, said data warehouses usually require five times the storage capacity that's needed for the data alone.