A system and method for the detection and termination of fraudulent services

A system (19) for automatic detection of fraudulent activity on a transaction network, for which each transaction over the network has an identifier associated with it, so that the system comprises: means (32) comparison voice, intended to compare a first voice (44) of a user, which has been sampled, a first transaction, with a voice (44) from which samples were taken subsequent manner and belonging to a user a subsequent transaction having an identical to the first transaction identifier, and control means (26) for determining, from said comparison, a profile of user usage that is representative of a number of different users of the identifier, to in order to compare the profile of user usage with a threshold for fraudulent use and for generating a signal (40) state of fraud in case the user usage profile exceeds the threshold.