Question: When a UE sends SIP requests using a Public User Identity for which both P-GRUU and T-GRUU are available, what should the UE use as the Contact address if the user does not require privacy?
Option 1: Always use the T-GRUU to ensure temporary routing for security.
Option 2: Randomly select between the retained P-GRUU and a T-GRUU for load balancing.
Option 3: Use the most recently obtained GRUU, regardless of type (P-GRUU or T-GRUU).
Option 4: Use the corresponding retained P-GRUU as the Contact address.
Explanation: According to guidelines for handling GRUUs in SIP requests, if a UE has obtained both P-GRUU and T-GRUU for its Public User Identity being used and the user does not require privacy, the UE should utilize the P-GRUU as the Contact address. This provides a stable, globally routable URI for direct routing to the UE when privacy is not a concern, enhancing communication setup efficiency.