Question: What is a consequence for the S-CSCF when the Nhss_ImsUECM_Registration service operation is successfully executed for an IMS User, assuming no explicit deregistration action is taken afterwards?
Option 1: The S-CSCF will periodically poll the HSS for user registration status updates.
Option 2: The S-CSCF is explicitly unsubscribed from all future notification operations related to the registered IMS User.
Option 3: The S-CSCF's assignment to the IMS User is set to expire after a predefined, standard timeout period.
Option 4: The S-CSCF is implicitly subscribed to receive a Nhss_ImsUECM_DeregistrationNotification when the IMS User is deregistered in HSS.
Explanation: As part of the Nhss_ImsUECM_Registration service operation, the S-CSCF is implicitly subscribed to be notified when it is deregistered in the Home Subscriber Server (HSS), via the Nhss_ImsUECM_DeregistrationNotification operation, ensuring the S-CSCF remains updated on the user's registration status upon any future deregistration event.