Question: Upon receiving an original Mobile Terminated (MT) Short Message (SM), how does a replying Mobile Station (MS) determine if a reply path exists for responding to the message?
Option 1: By checking the presence of TP-Reply-Path in the SMS-DELIVER PDU (set indicates existence, not set indicates non-existence)
Option 2: Through the RP-Originating-Address in RPS-MT-DATA, which directly implies reply path availability
Option 3: Based on the TP-Originating-Address in the SMS-DELIVER PDU, which inherently signals reply path existence or non-existence
Option 4: By analyzing the originating SME address for specific reply path indicators
Explanation: According to the technical realization of the Short Message Service (SMS), a replying MS determines the existence of a reply path by checking the TP-Reply-Path parameter within the SMS-DELIVER PDU. If this parameter is set, it indicates that a reply path exists for responding to the message; if not set, it signifies the absence of a reply path. This method directly relates to how the MS interprets received MT SMs for potential responses, highlighting the importance of TP-Reply-Path in SMS exchange protocols.