Question: When a PCRF receives an INITIAL_REQUEST with IMS Signalling Priority set and a Called-Station-Id AVP corresponding to an APN dedicated for IMS, what action does the PCRF take regarding the default bearer's ARP?
Option 1: Derive the ARP without considering IMS Signalling Priority
Option 2: Assign an ARP corresponding to Multimedia Priority Services (MPS) for the default bearer
Option 3: Initiate a RAR command to query additional priority information from the SPR
Option 4: Apply a default QCI value without altering the ARP
Explanation: According to the described behavior, when IMS Signalling Priority is set and the Called-Station-Id AVP corresponds to an APN dedicated for IMS, the PCRF assigns an ARP corresponding to MPS (Multimedia Priority Services) for the default bearer. This prioritizes traffic appropriately for IMS services when all conditions are met.