Question: In a RANflex configuration for Voice Group Call Service (VGCS), what triggers the second GCR (Group Call Register) interrogation in the anchor MSC when it is also the group call serving MSC?
Option 1: Receipt of the MAP service SEND_GROUP_CALL_INFO from the VMSC
Option 2: Service subscriber's initial talker request to join the voice group call
Option 3: Completion of the first GCR interrogation by the relay MSC
Option 4: Receiving the IAM (Initial Address Message) from the VMSC
Explanation: In a RANflex configuration for VGCS, when the anchor MSC is also serving the group call, the second GCR interrogation is specifically triggered by receiving the Initial Address Message (IAM) from the Visited Mobile Switching Center (VMSC). This IAM signifies the setup of the voice group call, prompting the need for the second interrogation to retrieve transient data stored during the first interrogation, ensuring seamless call establishment with the correct talker information.