Question: In a VoLTE roaming scenario with Local Breakout (LBO) architecture, where do the PDN-GW and P-CSCF reside, and what implication does this have on Lawful Interception (LI) awareness between networks?
Option 1: PDN-GW and P-CSCF reside in the Home Public Land Mobile Network (HPLMN), allowing for shared LI awareness between HPLMN and Visited Public Land Mobile Network (VPLMN).
Option 2: PDN-GW and P-CSCF reside in the Visited Public Land Mobile Network (VPLMN), but LI activities are centrally managed and visible to both VPLMN and Home Public Land Mobile Network (HPLMN).
Option 3: PDN-GW and P-CSCF reside in the Visited Public Land Mobile Network (VPLMN), resulting in independent LI performances in both VPLMN and Home Public Land Mobile Network (HPLMN) without mutual awareness.
Option 4: PDN-GW resides in the HPLMN, while P-CSCF resides in the VPLMN, necessitating a shared LI database between networks for coordination.
Explanation: In Local Breakout (LBO) architecture for VoLTE roaming, the PDN Gateway (PDN-GW) and Proxy-Call Session Control Function (P-CSCF) are located in the Visited Public Land Mobile Network (VPLMN). This setup means that Lawful Interception (LI) activities conducted by the VPLMN are independent of those by the Home Public Land Mobile Network (HPLMN), and vice versa, with no inherent mutual awareness or sharing of LI information between the two networks. This highlights the importance of understanding the implications of roaming architectures on security and surveillance functionalities in telecom networks.