Question: What is a key requirement for executing Voice Call Continuity (VCC) in a 3GPP system when a user transitions between CS domain and IMS?
Option 1: The UE must support dual-radio capability to maintain simultaneous connections.
Option 2: The transition must be based on operator policy, triggered by a change in the UE's connection to the 3GPP system as the user moves between domains.
Option 3: The user's IMS services and CS domain must belong to the same operator.
Option 4: The voice service can only continue if the UE is within the home network, not while roaming.
Explanation: Voice Call Continuity (VCC) in a 3GPP system is executed based on operator policy when there's a need to continue a voice service across a change in the UE's connection from CS domain to IMS or vice versa, ensuring uninterrupted user experience. This highlights the importance of operator policy and network transition as triggers for VCC, rather than device capabilities, same-operator requirement, or location within the home network.