NCJ Number
166240
Journal
Journal of Forensic Identification Volume: 46 Issue: 3 Dated: (May/June 1996) Pages: 294-322
Date Published
1996
Length
29 pages
Annotation
To determine the possible uniqueness of hang-up transient signatures for forensic applications, 28 analog telephones of the same type were tested.
Abstract
Telephone calls were made at five different times from the Federal Bureau of Investigation's engineering facility in Quantico, Virginia, and recorded at a private residence 15 miles away. Three waveform analysis procedures were used to examine recorded signal transients: number of events, temporal spacing, and general shaping. Results demonstrated that only half of the telephones had a consistent number of transients (two or three), that transient spacing varied for each telephone but primarily within the same general range, and that all telephones except one had nearly identical shaping of the first and last transients. Until further research is conducted, the authors recommend caution in using the hang-up transient signature technique in forensic applications to identify or eliminate a telephone instrument. 5 references, 7 tables, and 6 figures