SIM, eSIM, iSIM — from physical to integrated

Three Generations of SIM

SIM technology has evolved through three generations. Physical SIM: a removable smart card (full-size, micro, nano) housing a SIM applet on a secure chip. The applet stores the operator's root key (K), the IMSI, and other subscription data. The chip executes AKA authentication challenges, computing responses based on K without ever exposing the key. Physical SIMs are operator-issued and replaced if the customer changes operators. eSIM (embedded SIM): the SIM chip is soldered to the device PCB rather than being removable. eSIM supports remote profile management — profiles (operator…