UE with integrated subscriber identity modules by resource sharing

A Narrowband Internet of Things device (UE), comprising a modem and an integrated Subscriber Identity Module (iSIM) both combined on a modem chip, wherein identical components of the modem and the iSIM are designed as shared components, and the shared components are cryptographic accelerators that are used in the iSIM for network authentication and provisioning and in the modem for secure boot, firmware encryption and integrity checking and encryption of network packets, or end-to-end data protection with Datagram Transport Layer Security, whereas a secure hardware arbiter manages an access to the shared components by the modem or the iSIM and prevents information leaking, wherein the hardware arbiter comprises a timer for preventing blocking of the shared components.