Question: In a VPLMN with untrusted non-3GPP IP access via WLAN, where is Lawful Interception (LI) performed according to LI requirements for PDG for I-WLAN?
Option 1: At the PDN-GW upon DSMIP registration/tunnel activation
Option 2: At the ePDG (Evolved Packet Data Gateway)
Option 3: Directly at the WLAN Access Point (AP) for all S2c connections
Option 4: Within the UE (User Equipment) for localized interception
Explanation: In the context of untrusted non-3GPP IP access, such as via a Wireless Local Area Network (WLAN), the ePDG serves as a critical entry point for securing and managing traffic. Lawful Interception (LI) requirements for PDG (Packet Data Gateway) in I-WLAN scenarios necessitate performing LI at this gateway to ensure all incoming and outgoing traffic can be monitored as required by legal standards, making **Option 2** the correct choice. This approach ensures that all S2c (the interface between the ePDG and the EPC - Evolved Packet Core) connections are subject to lawful interception without needing direct access to individual WLAN APs or modifying UE behavior.