Question: In a centralized IMS architecture for roaming users, as described in 3GPP standards, what happens to inbound roamers not supporting IMS or ICS in their Home Public Land Mobile Network (HPLMN)?
Option 1: A temporary IMS subscription is created, and service is handled locally in the VPLMN using IMS logic.
Option 2: They are redirected to a legacy CS service domain in the Visited Public Land Mobile Network (VPLMN) for service execution.
Option 3: Their access is restricted to PS (Packet Switched) services only, bypassing IMS capabilities.
Option 4: They are automatically upgraded to support IMS or ICS for the duration of their roaming period.
Explanation: In a centralized IMS architecture designed for all users roaming in a network, regardless of access type, inbound roamers without IMS or ICS support in their HPLMN require special handling. The correct approach involves creating a temporary IMS subscription, allowing local handling of services within the VPLMN using IMS logic, ensuring seamless integration without necessitating support from the roamers' home networks or altering their original capabilities.