Question: In an IMS session modification scenario, what triggers the P-CSCF to send a Diameter AAR for an existing Diameter session to authorize updated QoS resources?
Option 1: Receipt of the initial SDP offer from the originating side
Option 2: Completion of SIP signalling interaction with the terminating side without changes in SDP parameters
Option 3: Detection of irrelevant changes in the SDP by the P-CSCF
Option 4: Receipt of negotiated SDP parameters from the terminating side through SIP signalling, indicating relevant changes
Explanation: The correct trigger for sending a Diameter AAR to authorize updated QoS resources is after the P-CSCF receives and identifies relevant changes in the negotiated SDP parameters from the terminating side, essential for requesting QoS resource authorization from the PDF after synchronized service information exchange via SIP signalling.