3GPP43.069Release 16Stage 2TSVoice Broadcast Service (VBS)
A destination service subscriber shall automatically disconnect from the call when leaving the group call area.
If the calling subscriber leaves the group call area or enters a BSC area not belonging to the service area, the call shall be terminated by the network, once the network has detected that the calling subscriber has left the Group Call Area.
A destination subscriber’ mobile station shall leave the voice broadcast call by no longer listening to the voice broadcast channel downlink and returning to idle mode. A broadcast call is returned to by listening to the periodic notification messages for that call, and reacting on them appropriately.