Eric A Johnson, Michael D Liss, Flemming B Jensen: Apparatus and method for detecting fraudulent telecommunication activity. Coral Systems, Sheridan Ross & McIntosh, September 6, 1994: US05345595 (237 worldwide citation)

An apparatus for detecting potentially fraudulent telecommunication activity, comprising a digital computer; interface, operatively connected to the digital computer, for receiving a call information record for each call involving a particular subscriber; comparator operating within the digital comp ...