These GCHQ minutes from October 2008 describes how the agency and its partners can re-use voice recognition data in different situations: see the Intercept article Finding Your Voice, 19 January 2018.
This extract from the January 2008 minutes of GCHQ’s Voice/Fax User Group (VFUG) discusses a November 2007 visit to NSA and being shown a version of Voice RT, which is described as a “one-stop shop” for voice-related insights: see the Intercept article Finding Your Voice, 19 January 2018.
This undated GCHQ presentation gives an overview of the agency’s use of hacking techniques, including an explanation of what it perceived the legal position to be at the time: see the InterceptHow U.K. Spies Hacked a European Ally and Got Away With It, 17 February 2018.
This undated presentation from GCHQ’s Information and Communications Technology Research department discusses the agency’s efforts in finding “closed loops” of cheap burner phones, a major focus for the agency in the wake of the 7/7 London bombings: see the Intercept article How London’s 7/7 Bombings Led to “Unprecedented” Surveillance Tactics, 1 March 2018.
This undated GCHQ presentation, which includes speaking notes, outlines different techniques for contact chaining – moving from one contact to find all those associated with it: see the Intercept article How London’s 7/7 Bombings Led to “Unprecedented” Surveillance Tactics, 1 March 2018.
This page from GCHQ’s internal GCWiki, dated 24 April 2012 describes procedures for searching through financial data retained by the agency, and cites examples of some of its sources: see the Intercept article Airport Police Demanded An Activist’s Passwords. He Refused. Now He Faces Prison In The UK, 23 September 2017.