Question: Upon receiving an MNSMS-EST-Ind with a valid RP-SMMA in the Idle state, what action does the SMR entity in the SGSN take if SMS delivery via GPRS is not activated?
Option 1: Passes the SMS-TPDU to the SM-TL and starts timer TR2N.
Option 2: Enters the 'Wait to send RP-ACK' state without sending an acknowledgement.
Option 3: Sends an RP-ACK with a success indicator to the UE.
Option 4: Returns an RP-ERROR message with cause #69 'Requested facility not implemented' and remains in the Idle state.
Explanation: This is because, when the SMR entity in the SGSN is in the Idle state, receives a valid RP-SMMA but GPRS-based SMS delivery is not enabled, it responds with an error message indicating the requested facility (GPRS SMS delivery) is not implemented, thus staying in the Idle state. This action aligns with standard procedures for handling unsupported features in telecom networks, ensuring clarity on service availability to the user.