This method includes: The terminal (TM) starts a calling. IF the dispatch server (DS) resided currently by TM is the DS of the group residing area (GRA), after TM joins into this calling, the prepaiduser end (PUE) of GRA deducts the quota used by this calling. If it is not, after TM joins into this calling, DS of GRA interacts with the DS of the area where TM is now; and transfers synchronously to latter the corresponding prepaid info about this calling. PUE of either DS deducts the quota used by this calling depending on the charging mode. This invention solves the problem that prepaid of the un-going group calling user distributed in multi DSs is impossible in the existing grouped system.