Question: During an Inter-MSC Handover, if ciphering was already in progress before the handover, how is the chosen algorithm indicated to the 3G_MSC-B for continued ciphering control?
Option 1: In the Handover Request BSSMAP message, with the chosen algorithm explicitly included.
Option 2: In the Handover Request Acknowledge message, with a dedicated field for the chosen algorithm.
Option 3: Through a separate Cipher Mode Command procedure initiated by MSC-A after handover completion.
Option 4: Not indicated; 3G_MSC-B infers from the stored list of allowed algorithms.
Explanation: According to the provided context, if ciphering was performed before the Inter-MSC Handover, the information about the chosen algorithm is included in the Handover Request BSSMAP message sent to 3G_MSC-B. This ensures continuity of ciphering with the correct algorithm after the handover.