Question: For an RRC_CONNECTED NB-IoT UE, what action does the eNB take if it detects the UE is in a different country than the one served by the current MME?
Option 1: The eNB performs an S1 handover to change to an appropriate MME and simultaneously initiates a UE Context Release Request procedure.
Option 2: The eNB only updates its internal records to reflect the UE's new location without altering the UE's connection to the current MME.
Option 3: The eNB initiates a UE Context Release Request procedure towards the serving MME, which may then decide to detach the UE.
Option 4: The eNB immediately detaches the UE from the network due to the location mismatch.
Explanation: This is the correct action for RRC_CONNECTED NB-IoT UEs. When an eNB detects a country mismatch, it initiates a UE Context Release Request towards the serving MME, allowing the MME to decide on next steps, which could include detaching the UE, ensuring location consistency and appropriate connection management based on geographical location.