Question: Where does the IMS Application Reference have significance in identifying IMS applications, according to 3GPP specifications?
Option 1: Only at the Serving and PDN Gateway (SGW/PGW) level
Option 2: At both the User Equipment (UE) and the SIP Application Server (SIP AS) behaving as SIP endpoints
Option 3: Exclusively at the Home Subscriber Server (HSS) for user profile management
Option 4: Primarily on the interfaces between the Radio Access Network (RAN) and the Core Network
Explanation: The IMS Application Reference is crucial for identifying specific IMS applications beyond the default service. Its significance is highlighted at two key endpoints: the User Equipment (UE), where end-users interact with services, and the SIP Application Server (SIP AS) acting as a SIP endpoint, which facilitates the communication service. This dual significance ensures seamless service provision and correct application identification across the network.