Question: In the UE Context Modification procedure, what action may an eNB take if a UE served by a CSG (Closed Subscriber Group) cell is no longer a member of that CSG cell and handover to another cell does not occur?
Option 1: Request the release of UE context
Option 2: Provide QoS for the UE as a non-CSG member without change
Option 3: Initiate a new UE Context Modification procedure with revised parameters
Option 4: Send an error message to the MME and terminate the procedure
Explanation: According to the specified behavior for UEs in a CSG cell who lose membership, if the eNB does not perform a handover to another cell, it should take the action of requesting the release of the UE's context. This ensures resources are managed properly and aligns with the procedural outcomes defined for changes in UE state or permissions within the network.