Patent ID: 10064048

Abstract:
A gateway (GW) acquires an International Mobile Subscriber Identity (IMSI) of a user equipment (UE) without requesting a mobile management entity (MME) of a core network (CN) to provide it. The GW detects arrival of a S1AP message for the UE. If the GW does not have the IMSI of the UE, and if a NAS payload of the S1AP message is ciphered, send to the UE a rejecting message indicating detaching the UE from the CN, causing the UE to request re-attaching to the CN in a S1AP message that is an Initial UE Message, which contains a temporary identifier of the UE. Then alter the Initial UE Message with a fabricated temporary identifier not recognizable by the MME and send the altered message to the MME, causing the MME to ask the UE to identify itself with the IMSI, which is read by the GW.