A transaction device, having an input portion, and a processing device, having a client file, which is located at a processing center, are connected by a telephone line for processing data input on the transaction device. The transaction device sends an alarm signal when a transaction is carried out...http://www.google.com/patents/US4675815?utm_source=gb-gplus-sharePatent US4675815 - Transaction safety system for falsely indicating successful completion of illegal transaction
