A network device of a core network may maintain a mapping table that maps core network slices with quality of service (QoS) class identifiers (QCIs) based on service profile identifiers (SPIDs), and may receive, from a user device, a request for service with a particular QCI included in the QCIs of the mapping table. The network device may identify a particular SPID of the SPIDs in the mapping table based on the particular QCI of the service, and may generate a flow request based on the particular SPID. The network device may cause the flow request to be provided to a radio access network (RAN) associated with the user device, to cause the RAN to select a RAN slice for provision of the service to the user device.