Question: In the context of Lawful Interception (LI) for IMS services, what action does the S-GW/BBIFF take regarding the GTP tunnel used for IMS Signalling Bearer when instructed by the Lawful Interception Management System Function (LMISF)?
Option 1: The S-GW/BBIFF encrypts all octets above the GTP layer before forwarding to the UE.
Option 2: The S-GW/BBIFF delivers all octets above the GTP layer to the LMISF along with associated IMS Signalling Bearer information.
Option 3: The S-GW/BBIFF modifies the APN of the S8HR to facilitate LI for media bearers only.
Option 4: The S-GW/BBIFF terminates the GTP tunnel upon receiving instructions from the LMISF.
Explanation: In lawful interception scenarios, transparency and completeness of intercepted data are crucial. By delivering all octets above the GTP layer to the LMISF (as instructed), the S-GW/BBIFF ensures that the intercepting authority receives comprehensive signalling information related to IMS services, facilitating effective lawful interception without altering or interrupting the service to the end-user.