Question: What is the mandatory transport protocol for SIP/SDP procedures over the W2 reference point (UE to eP-CSCF) as per Release 12 enhancements for IMS?
Option 1: TCP with TLS
Option 2: UDP with DTLS
Option 3: Secure WebSocket
Option 4: HTTP/2 with TLS
Explanation: According to the provided context, in Release 12 for IMS (IP Multimedia Subsystem), secure WebSocket is specified as the supported transport protocol for SIP over the W2 reference point between the UE (User Equipment) and the eP-CSCF (enhanced Proxy-Call Session Control Function), especially with enhancements for WebRTC (Web Real-Time Communication) access. This highlights the importance of secure WebSocket in facilitating secure, real-time communication sessions over this interface.