Question: During initial UE registration, how does a P-CSCF provision SIP signalling flow information to the PCRF if an Rx Diameter session is already open?
Option 1: The P-CSCF always initiates a new Rx Diameter session for SIP signalling flow information.
Option 2: The P-CSCF uses an existing Rx Diameter session only if it was opened for a different UE.
Option 3: The provisioning of SIP signalling flows is not possible via an already open Rx Diameter session.
Option 4: The P-CSCF reuses the already open Rx Diameter session related to the signalling with the UE.
Explanation: This is correct because, according to procedure, if the P-CSCF already has an open Rx Diameter session with the PCRF related to the signalling with the UE, it shall reuse this existing session to provision the SIP Signalling IP Flow information, optimizing resource utilization.