Question: In an MCPTT (Mission Critical Push To Talk) scenario, when an ongoing session is upgraded to an emergency group call with the "mc_implicit_request" fmtp attribute in the SDP offer, what action does the IWF (Interworking Function) floor control server take regarding its state?
Option 1: It transitions to 'Granted' state and notifies all MCPTT clients.
Option 2: It remains in the 'U: not permitted and Floor Taken' state but sends a release request.
Option 3: It enters a 'Pending' state awaiting further signaling plane updates.
Option 4: It indicates an implicit floor request to its arbitration logic and remains in the 'U: not permitted and Floor Taken' state.
Explanation: According to MCPTT media plane control specifications, when a session is upgraded to an emergency group call with the "mc_implicit_request" attribute, the IWF floor control server must signal the reception of an implicit floor request due to this upgrade. Simultaneously, to maintain control and order in the emergency communication scenario, it remains in a state that reflects no new permissions are granted ('U: not permitted and Floor Taken'), ensuring orderly communication during the emergency.