Question: In a Decorated NAI format for SUCI in 5G networks, what determines the 'otherrealm' part when a User Equipment (UE) is roaming on a non-subscribed Single Network Slice Provider (SNPN)?
Option 1: Home PLMN's MCC and MNC
Option 2: Visited PLMN's MCC and MNC for non-SNPN scenarios, but for SNPN scenarios, it uses the subscribed SNPN's NID, MNC, and MCC
Option 3: The 'otherrealm' always uses the Home PLMN's MCC and MNC, regardless of the roaming status or SNPN involvement
Option 4: The UE's IMSI directly influences the 'otherrealm'
Explanation: According to specifications for Decorated NAI format in SUCI contexts, when a UE is on a visited network, especially with SNPNs, the 'otherrealm' part is constructed differently based on whether it's a subscribed or non-subscribed SNPN scenario. For non-SNPN scenarios, it uses the visited PLMN's MCC and MNC. However, for SNPN scenarios, 'otherrealm' incorporates elements (NID, MNC, MCC) identifying the non-subscribed SNPN when the UE isn't subscribed to the accessed SNPN, highlighting nuanced handling based on subscription status and network type.