A system for registering an MSISDN associated with a device hosting a UICC and in which the UICC is or can be operated, the MSISDN being registered at a mobile network operator MNO server operated by an MNO; the system comprising the following elements: - the device, - the UICC, - a UICC provisioning server (DP+) being operated by an UICC owner or editor which is different from the MNO, - a Local Profile Assistant LPA installed within the device or within the UICC, and enabling establishment and operation of secured data sessions between the UICC and the UICC provisioning server (DP+), - a modem installed within the device or within the UICC, and enabling communication of the device within a mobile network operator MNO mobile network, the modem having access to the MSISDN of the device, characterized in that the system further comprises: - an MSISDN retrieval logic installed within or associated with the Local Profile Assistant LPA, and constructed to perform a retrieval sequence comprising the steps: (1,2) retrieving the MSISDN from the modem to the LPA, (3,4) providing the retrieved MSISDN from the LPA to the UICC and storing the MSISDN in the UICC in a non-volatile manner, by the LPA, establishing a secured data session between the UICC and the UICC provisioning server (DP+), and (6,7) by the UICC provisioning server (DP+), retrieving the MSISDN from the UICC via the established secured data session and registering the MSISDN as associated with the device hosting the UICC at the UICC provisioning server (DP+) without requesting information from any MNO server. - the device, - the UICC, - a UICC provisioning server (DP+) being operated by an UICC owner or editor which is different from the MNO, - a Local Profile Assistant LPA installed within the device or within the UICC, and enabling establishment and operation of secured data sessions between the UICC and the UICC provisioning server (DP+), - a modem installed within the device or within the UICC, and enabling communication of the device within a mobile network operator MNO mobile network, the modem having access to the MSISDN of the device, - an MSISDN retrieval logic installed within or associated with the Local Profile Assistant LPA, and constructed to perform a retrieval sequence comprising the steps: (1,2) retrieving the MSISDN from the modem to the LPA, (3,4) providing the retrieved MSISDN from the LPA to the UICC and storing the MSISDN in the UICC in a non-volatile manner, by the LPA, establishing a secured data session between the UICC and the UICC provisioning server (DP+), and (6,7) by the UICC provisioning server (DP+), retrieving the MSISDN from the UICC via the established secured data session and registering the MSISDN as associated with the device hosting the UICC at the UICC provisioning server (DP+) without requesting information from any MNO server. (1,2) retrieving the MSISDN from the modem to the LPA, (3,4) providing the retrieved MSISDN from the LPA to the UICC and storing the MSISDN in the UICC in a non-volatile manner, by the LPA, establishing a secured data session between the UICC and the UICC provisioning server (DP+), and (6,7) by the UICC provisioning server (DP+), retrieving the MSISDN from the UICC via the established secured data session and registering the MSISDN as associated with the device hosting the UICC at the UICC provisioning server (DP+) without requesting information from any MNO server.