Question: In an IMS network supporting ICE and Outbound procedures but not IMS-ALG, what happens when a User Equipment (UE) modifies an existing media flow during a session modification procedure?
Option 1: The existing media flow is always directly modified without affecting other flows.
Option 2: A new media flow is established, and the existing one is released, following session termination procedures for the old flow.
Option 3: The UE initiates a new session establishment procedure for all media flows.
Option 4: The network rejects the session modification if it involves an existing media flow.
Explanation: According to IMS session management principles, when an existing media flow is modified during a session update (and the network supports ICE and Outbound but not IMS-ALG), this leads to establishing a new media flow for the changes, while terminating the existing flow. This ensures seamless handover to the new configuration without interrupting the overall session, with the new flow setup following initial procedures and resource cleanup via termination procedures for the old flow.