Abstract: In order to request the presentation of an operator indicator in a user's terminal having a first mobile terminal connected to a first cellular radiocommunications network, the operator is related to a second mobile terminal whose call number is stored in the user's terminal and is transmitted therefrom to a server of the first network. The server compares the transmitted call number with call numbers of the first network mobile terminal contained in a first list, in such a way that it is enabled to read the operator indicator corresponding to the transmitted call number. A module in the form of a UICC card stores the indicator and submits it to the user for informing the user whether the call number belongs to the first network or belongs to another network.