A core network receives data from at least one of an AF, a DN, or a UE. A UPF having small data capability processes the data for transport with a low overhead and without initiating a bearer set up protocol. The data may be transported between the UE and the UPF as an RRC payload over a NAS protocol. The data may be received from an AF or DN external to the core network and may be processed to transport the data to the UE based as an RRC payload. The data may be received as uplink data from a UE, e.g., in an RRC payload. The UPF may process the RRC payload to obtain the data and may transport the data to the AF or DN. The UPF may perform IP header compression, data encryption, and/or buffering of data for a UE in an idle mode.