Question: In a Voice Group Call Service (VGCS) scenario, what information can be included in a Sync GCR (Group Call Reference) negative response when indicating an 'on-going call'?
Option 1: Only the identity of the initial talker and the reason for failure.
Option 2: The MSC (Mobile Switching Center) address of the MSC within the redundancy pool where the group call is ongoing.
Option 3: Details of all participants in the on-going group call.
Option 4: The scheduled end time of the on-going group call.
Explanation: When a Sync GCR negative response indicates an 'on-going call', providing the MSC address of the MSC within the redundancy pool where the group call is ongoing is crucial. This information helps in managing and routing subsequent requests efficiently, ensuring seamless communication within the telecom network.