Question: In a 3GPP IMS (IP Multimedia Subsystem) environment, for sessions utilizing CS (Circuit Switched) media established by an ICS (IMS Centralized Services) UE, how can the addition or removal of video media flow be achieved if SCUDIF (Service Centralization and Continuity Using Diameter Interface for Forecasting) procedures are not supported?
Option 1: By initiating a new SIP (Session Initiation Protocol) invite for the updated media configuration over the IP access leg.
Option 2: Through SMS (Short Message Service) messaging to request media flow updates on the CS access leg.
Option 3: Using a redial mechanism over the CS access leg, as defined in 3GPP specifications for service modification.
Option 4: Automatically by the network upon detection of device capability changes.
Explanation: In the absence of SCUDIF support for updating CS media flows in an IMS session within a 3GPP system, utilizing a redial mechanism over the CS access leg is the specified alternative approach. This method, defined by 3GPP for handling service modifications when more direct update mechanisms are not available, ensures continuity and flexibility in managing multimedia sessions across different access types.