Question: What is a key characteristic of a non-IMSI based USIM (Universal Subscriber Identity Module) in terms of its implementation and structure on a UICC (Universal Integrated Circuit Card)?
Option 1: It must be implemented as a standalone application on a dedicated UICC, separate from any IMSI-based USIM.
Option 2: It can only coexist with an IMSI-based USIM on the same UICC if it's a simplified version, lacking some mandatory EFs (Elementary Files).
Option 3: It may be implemented either as a single USIM application on a UICC or as a secondary USIM application alongside an IMSI-based USIM on one UICC, containing all mandatory EFs except EFIMSI.
Option 4: Its implementation requires a hybrid UICC that supports both USIM and another non-USIM application type simultaneously.
Explanation: This option correctly reflects the flexibility in implementing a non-IMSI based USIM, either as a sole application on a UICC or concurrently with an IMSI-based USIM on the same card. It also accurately notes that such a USIM contains all mandatory EFs defined for a standard USIM application, with the exception of EFIMSI, highlighting its compliance with standard USIM requirements minus the IMSI-specific aspect.