From Seymour Hersch, The New Yorker:
A security consultant working with a major telecommunications carrier told me that his client set up a top-secret high-speed circuit between its main computer complex and Quantico, Virginia, the site of a government-intelligence computer center. This link provided direct access to the carrier’s network core—the critical area of its system, where all its data are stored. “What the companies are doing is worse than turning over records,” the consultant said. “They’re providing total access to all the data.”
“This is not about getting a cardboard box of monthly phone bills in alphabetical order,” a former senior intelligence official said. The Administration’s goal after September 11th was to find suspected terrorists and target them for capture or, in some cases, air strikes. “The N.S.A. is getting real-time actionable intelligence,” the former official said.
Here.