Access of a user to a resource, such as a telecommunications network, includes storing, in a first call data base, a first set of attributes concerning an ongoing call from a caller. A second call data base stores a second set of attributes concerning the history of prior calls made by the caller. A...http://www.google.de/patents/US5495521?utm_source=gb-gplus-sharePatent US5495521 - Method and means for preventing fraudulent use of telephone network
