Question: What is the primary factor considered by the UDM selection functionality in NF consumers or SCP when selecting a UDM instance for user subscriptions?
Option 1: Home Network Identifier (e.g., MNC and MCC, realm) of SUCI/SUPI
Option 2: UDM Group ID of the UE's SUPI
Option 3: SUPI or Internal Group ID
Option 4: GPSI or External Group ID
Explanation: According to the 3GPP TS 23.501 specification, the primary factor considered by the UDM selection functionality in NF consumers or SCP when selecting a UDM instance for user subscriptions is the Home Network Identifier (e.g., MNC and MCC, realm) of SUCI/SUPI. This identifier provides information about the home network of the subscriber, which is essential for selecting the correct UDM instance.