An overall architecture to integrate multicast and broadcast service into a general 5G core network. The architecture may provide methods and systems to switch the delivery mode of transmitting messages to User Equipment (UE)s from a unicast mode to a multicast mode. The method includes triggering events at UE, network functions, content provider or RAN node to initiate the switch process; a procedure for UE initiated switch from unicast to multicast; a procedure for network-initiated switch from unicast mode to multicast mode; and a procedure for RAN initiated switch from unicast mode to multicast mode. The architecture may also provide methods to switch the delivery mode from multicast mode to unicast mode. These methods may include triggering events at UE, network functions, content provider or RAN node to initiate the switch process; a procedure for UE initiated switch from multicast mode to unicast mode; a procedure for network-initiated switch from multicast mode to unicast mode; and a procedure for RAN initiated switch from multicast mode to unicast mode.