Question: In a Voice Group Call Service (VGCS) scenario, when a service subscriber's mobile station changes cells within the group call area, what does it primarily rely on to determine the appropriate channel for retuning to continue the voice group call in the new cell?
Option 1: Periodic broadcast on the downlink SACCH of neighboring cells' identities.
Option 2: Listening to both the Broadcast Control Channel (BCCH) and the Normal Control Channel (NCH) of the target cell.
Option 3: An algorithm based solely on signal strength from neighboring cells.
Option 4: Location Area Update response from the network.
Explanation: For a mobile station to seamlessly continue a voice group call when entering a new cell, it must identify the correct channel to retune to. This is achieved by listening to the Broadcast Control Channel (BCCH) and the Normal Control Channel (NCH) of the target cell, as these channels broadcast essential system information and control data necessary for the mobile station to synchronize with the new cell's configuration and continue the call without interruption. This process ensures minimal disruption to the ongoing voice group call service.