Transaction Authorisation

A method for evaluating a remote transaction for the likelihood of fraud in an out-of-band authentication system in which a transaction processing system receives, from a remote user, a request to complete a first remote transaction over the Internet, the method comprising:

• receiving, from-a the transaction processing system, a request to evaluate-a the first remote transaction;
• identifying a telephone number of a telephone associated with the remote user in a database;
• requesting, from a telephone network operator associated with the identified telephone number, a subscriber identity associated with the identified telephone number;
• comparing the subscriber identity received from the telephone network operator with a primary stored subscriber identity associated with the remote user;
• assigning a value to the first remote transaction, the value depending at least in part on whether the received subscriber identity matches the primary stored subscriber identity;
• and
• communicating the value to the transaction processing system such that the transaction processing system can communicate authentication information with the remote user via a telephone call to the telephone or a message sent to the telephone depending upon the assigned value.