Question: In the context of IMS call disconnection, what does the protocol header field parameter value '01' represent in the Reason header field of a SIP message?
Option 1: Q.850 Protocol
Option 2: SS7 MTP Protocol
Option 3: H.323 Protocol
Option 4: Session Initiation Protocol (SIP)
Explanation: According to the specified coding for protocol header field parameters in IMS call disconnection, '01' is explicitly defined to represent SIP (Session Initiation Protocol), which is a protocol used for initiating, maintaining, and terminating real-time communication sessions over IP networks. This highlights the importance of accurate protocol identification in managing and troubleshooting IMS call disconnections in telecom networks.