subsequent implementation of a SIM function in a security module.

Process for the subsequent implementation of a SIM function, a security module (3), with the aid of a mobile phone (1) allows the use of a mobile network, so that: - the function SIM takes the form of an application, which is loaded at least a first part in the security module (3); - personalization data necessary for use of the mobile network by the mobile telephone (1) are transmitted by a provider (2), directly or indirectly, in coded form, the security module (3); - the security module (3) decodes the coded data customization, with the help of a secret key stored in the security module (3); and - with the help of decoded data customizing the security module (3) is customized.