Question: In the context of IP Multimedia Core Network Subsystem, what is the primary purpose of the IMS AKA protocol between the UE and the IMS before granting access to IM-services?
Option 1: To establish a secure transport service with associated QoS in the Visited Network.
Option 2: To perform mutual authentication between the UE and the IMS, ensuring both parties' identities are verified.
Option 3: To download the subscriber profile from the HSS to the S-CSCF over the Cx-reference point.
Option 4: To authorize bearer resources in the Home Network for IM-services.
Explanation: IMS AKA (Authentication and Key Agreement) is a protocol derived from UMTS/EPS AKA, specifically designed for secure mutual authentication between the User Equipment (UE) and the IP Multimedia Subsystem (IMS). This process ensures that both the UE's identity is confirmed to the IMS and vice versa, securing access to IM-services. This aligns with the principle of secure authentication protocols in telecom networks, where mutual verification is crucial for security.