According to leaked documents obtained by The Washington Post, the NSA currently has the capability to record 100% of a country's phone calls, enabling playback of any individual call for up to 30 days. The voice interception tool, dubbed MYSTIC, was launched in 2009 and became fully operational in 2011. According to the Post, it's currently deployed in at least one country and has been considered for use in others, although the paper declined to name the specific nations involved for reasons of national security.
The program is an all-encompassing wiretap
According to a classified summary, the program is a comprehensive and all-encompasing wiretap, recording "every single" conversation, and storing it for retrospective analysis up to a month after the fact. It also goes far beyond previously reported metadata collection programs, which captured phone numbers and call times but not the audio of the call itself. There's also reportedly no effort to filter out American calls caught in the dragnet, with any US numbers classified as "acquired incidentally as a result of collection directed against appropriate foreign intelligence targets." Below is the cover of an NSA slide deck describing the system, obtained by The Washington Post.
Other U.S. agencies also have access to the MYSTIC database, making it uniquely valuable when a new suspect or phone number is discovered. The program was first developed as a one-off capability, but the Post's documents show officials considering deploying it in as many as six other countries. Responding to the story, an NSA spokesperson emphasized that the NSA's job is to "identify threats within the large and complex system of modern global communications," and that all the agency's work is "strictly conducted under the rule of law."