Question: Which protocol is used by the GM-S reference point for subscription/notification related signaling in the context of group management functions between VAL servers and the Group Management Server?
Option 1: HTTP/2 (Hypertext Transfer Protocol version 2)
Option 2: SIP-2 (Session Initiation Protocol version 2)
Option 3: Diameter
Option 4: SMPP (Short Message Peer-to-Peer)
Explanation: The correct answer is SIP-2 because it is utilized for handling subscription and notification signaling in GM-S reference point interactions related to group management, highlighting SIP's role in managing real-time communication aspects within telecom networks.