"The National Security Agency has built a surveillance system capable of recording “100 percent” of a foreign country’s telephone calls, enabling the agency to rewind and review conversations as long as a month after they
“The National Security Agency has built a surveillance system capable of recording “100 percent” of a foreign country’s telephone calls, enabling the agency to rewind and review conversations as long as a month after they take place, according to people with direct knowledge of the effort and documents supplied by former contractor Edward Snowden.”
See the full article: NSA surveillance program reaches ‘into the past’ to retrieve, replay phone calls (Washington Post, link)
See documents: Mystic (2 pages, pdf) and: Scalwag/Retro (pdf)
This follows the revelation last year (October 2013) about the NSA mass collection of e-mail addresses: See: NSA collects millions of e-mail address books globally (Washington Post, link)