AF: Application Function

AF — Application-Aware Network Control

The Application Function represents any application that needs to interact with the 5G core to influence traffic routing or request specific quality of service. An AF can be trusted and internal to the operator domain, in which case it communicates directly with the PCF via the N5 interface. Alternatively, an AF can be external and untrusted, in which case it must access the core through the NEF for security. This dual-path design lets operators deploy their own applications with direct core access while keeping third-party applications safely isolated behind the NEF API gateway.