Question: What action does the VLR take upon receiving an SCCP connection establishment with the Initial L3 message from the UE via the A or Iu interface, in the context of returning to the last used E-UTRAN PLMN after CS fallback?
Option 1: Starts timer Ts15 to supervise the success of the UE fallback
Option 2: Stops timer Ts15 and applies specific handling related to the return to the last used E-UTRAN PLMN after CS fallback
Option 3: Considers the MO CSFB to have failed and does not apply specific handling for return to E-UTRAN
Option 4: Sends an SGsAP-MO-CSFB-INDICATION to the MME
Explanation: Upon receiving the SCCP connection establishment with the Initial L3 message from the UE, it indicates a successful step in the CS fallback process. Therefore, the VLR stops the supervising timer (Ts15) and proceeds with specific handling to support the UE's return to the last used E-UTRAN PLMN after the fallback, ensuring seamless network transition for the UE.