Mark Klein

Mark Klein is a former AT&T technician and whistleblower who revealed details of the company's cooperation with the United States National Security Agency in installing network hardware at a site known as Room 641A to monitor, capture and process American telecommunications. The subsequent media coverage became a major story in May 2006. He wrote a book about the NSA and AT&T's cooperation in surveiling everyone on the internet and his experience in discovering it and trying to tell the public called Wiring Up The Big Brother Machine...And Fighting It.

In recognition of his actions, the Electronic Frontier Foundation picked Klein as one of the winners of its 2008 Pioneer Awards.

For over 22 years Mark Klein worked for AT&T. Starting with the company as a Communications Technician in New York, where he remained from November 1981 until March 1991, he later continued in that capacity in California until 1998. From January 1998 to October 2003, Klein worked as a Computer Network Associate in San Francisco. Starting in October 2003, he returned to the role of Communications Technician, after which he retired in May 2004.