the former SBC), Verizon, and BellSouth connected nearly 500 billion telephone calls in 2005 and nearly two trillion calls since late 2001. It is reported that all four companies were paid to provide the information to the NSA. Usage Although such a database of phone records would not be useful as a tool in itself for national security, it could be used as an element of broader national security analytical efforts and data mining. These efforts could involve analysts using the data to connect phone numbers with names and links to persons of interest. Such efforts have been the focus of the NSA's recent attempts to acquire key technologies from high tech firms in Silicon Valley and elsewhere. Link analysis software, such as Link Explorer or the Analyst's Notebook, is used by law enforcement to organize and view links that are demonstrated through such information as telephone and financial records, which are imported into the program from other sources. Neural network software is used to detect patterns, classify and cluster data as well as forecast future events. Using relational mathematics, it is possible to find out if someone changes their telephone number by analyzing and comparing calling patterns. ThinThread, a system designed largely by William Binney, which pre-dated this database, but was discarded for the Trailblazer Project, introduced some of the technology which is used to analyze the data. Michael Hayden, former director of the NSA, admitted as much in an interview, saying: "But we judged fundamentally that as good as [ThinThread] was, and believe me, we pulled a whole bunch of elements out of it and used it for our final solution for these problems, as good as it was, it couldn't scale sufficiently to the volume of modern communications." Where ThinThread encrypted privacy data, however, no such measures have been reported with respect to the current system. Response In response, the Bush administration defended its activities, while neither specifically confirming or denying the existence of the potentially illegal program. According to the Deputy White House Press Secretary, "The intelligence activities undertaken by the United States government are lawful, necessary and required to protect Americans from terrorist attacks." Senator Arlen Specter claimed he would hold hearings with the telecommunications CEOs involved. The Senate Intelligence Committee was expected to question Air Force General Michael Hayden about the data-gathering during his confirmation hearings as Director of the Central Intelligence Agency. Hayden