Abstract: The invention concerns a method, and the related apparatuses, for authorizing mandates of payment through credit instruments, a user being the owner of at least one credit instrument, which is issued by an issuing institution (21) and of a telephone (20), which is provided with the functionality of sending and receiving radiotelephony messages, the method comprising the phases of A. the issuing institution checks the validity of the credit instrument, and B. the issuing institution sends to the commercial site a confirmation or refusal of authorization of the mandate of payment, C. sending from the use's telephone (20) to a radiotelephony message managing device (22) of a service center (21) of the issuing institution a radiotelephony message comprising a commercial site identification code, the amount of money and/or instrument identification data and/or user identification data and/or telephone identification data.