TRANSACTION AUTHORIZATION USING A VOCALIZED CHALLENGE

A method of transaction authorization, includes, at a server: receiving, from a computerized transaction system, transaction request data responsive to a user having initiated a transaction via the transaction system; instructing to generate a single use, one-time challenge, vocalized by voice synthesis and call a computerized electronic device of the user, using an endpoint identifier linked to the user, the latter enrolled at the server, to vocally communicate the vocalized challenge to the user; and communicating with the transaction system to validate response data sent by the user, in response to the vocalized challenge, to one or both of the server and the transaction system for validation, to authorize the transaction.