Question: In a SIP session setup, prior to receiving a 2xx response to the INVITE request, how may a P-CSCF handle media IP flows for multiplexed RTP/RTCP flows (negotiated using "a=rtcp-mux" SDP attribute) based on operator policy?
Option 1: Set Flow-Status to "ENABLED" to prevent RTCP blocking, regardless of operator policy.
Option 2: Enable or disable media IP flows based solely on operator policy, without considering the multiplexing aspect.
Option 3: Downgrade Flow-Status values derived from SDP direction attributes for all flows, including multiplexed RTP/RTCP.
Option 4: Suspend handling of media IP flows until the 2xx response is received.
Explanation: For multiplexed RTP/RTCP flows (using "a=rtcp-mux" SDP attribute), a P-CSCF must set the Flow-Status to "ENABLED". This is crucial to prevent RTCP from being blocked, ensuring proper communication. This handling takes precedence over general operator policy considerations for the duration before the SIP session setup is complete (i.e., before the 2xx response to the INVITE request).