1. A method comprising: comparing a first voice signal associated with a user against a database of known fraudulent voice signatures, wherein the first voice signal corresponds to word patterns used previously by people engaged in fraud securing a transaction of a credit card; identifying the first voice signal as fraudulent when the first voice signal substantially matches an entry in the database of known fraudulent voice signatures; comparing a second voice signal against a speaker verification database of voice signals associated with the credit card when the first voice signal is not identified as fraudulent, wherein the second voice signal comprises an uncommonly spoken word; requesting a third voice signal containing personal information for the user associated with the first voice signal and associated with the credit card when the first voice signal does not substantially match an entry in the speaker verification database for the user; and adding the first voice signal to the database of known fraudulent voice signatures when the personal information cannot be verified.