Discovering records of private VoIP calls without wiretapping

Abstract

Call-record analysis is one of the oldest tools used in defense, law-enforcement, and business intelligence. For example, the NSA collected over 1.9 trillion call records between 2001 and 2004 [1]. A call-record database allows both single link (e.g., time, initiation, frequency of a call) and cluster analysis of calls in the temporal, spatial, and frequency domains. It can also indicate overlaps among different clusters, such as those obtained from different investigations, and similarity of clusters, such as those obtained when a group of targets changes their phone numbers but not their communication habits [10, 12].