Extracting Dialed Telephone Numbers from Unstructured Audio
Steven Presser, Michael Walsh · 2018
presented is a novel method (the Call Contents Automatic Differentiator (CCAD)) for extracting dialed telephone numbers from unstructured audio without capturing audio content – including other dialed information. This technology fills a critical law enforcement need to determine the ultimate destination of a call, even when the call is routed through multiple redirectors. The basic methodology involves examining the timing between digits, as well as the volume of audio segments between digits. Despite its simplicity, this method was able to isolate and extract dialed telephone numbers with accuracy greater than 99% in the expected scenario and greater than 98% in worst-case scenarios. If expanded to work in real-world scenarios, CCAD could serve as a new and clearly-legal source of information for local, state and national law enforcement, as well as operating in national security cases.