A network device receives a first message that includes an identifier (ID) of a first User Plane Function (UPF), serving a first device, in a wireless network, where the first message invites a second device to engage in a session with the first device and where the first UPF supports packet routing and forwarding within the wireless network. The network device extracts the ID of the first UPF from the first message and determines a closest media resource function (MRF) to the first UPF, where the MRF processes and routes media streams between devices. The network device assigns the determined MRF as an anchor, in a network path between the first device and the second device, for processing and routing of media streamed between the first device and the second device.