Method and system for authorising a commercial transaction

The present invention relates to a method for authorizing a transaction of a customer by an authorization service provider, wherein the authorization service provider has stored in a memory a customer's reference voice pattern associated with an identifier of the customer, comprising:Establishing a communication link between a customer and the authorization service provider;Transmitting an identifier from the customer to the authorization service provider;Transmitting a word sequence generated by the authorization service provider to the customer that was not previously known to the customer;Postponing the phrase and transmitting the postponed word order from the customer to the authorization service provider;Comparing the repeated word sequence and the stored reference pattern associated with the transmitted identifier for agreement with respect to characteristic voice characteristics;Authorizing a transaction of the customer if the correspondence between the repeated word sequence and the stored reference pattern associated with the transmitted identifier is greater than a predetermined threshold.