SCEF to NEF evolution: what changed from 4G to 5G

SCEF: The 4G Predecessor

Before 5G introduced the NEF, 4G networks exposed capabilities through the Service Capability Exposure Function. The SCEF connected external applications to the EPC via the T8 API, enabling features like device triggering, non-IP data delivery for NB-IoT, and monitoring events such as UE reachability. However, SCEF had significant limitations. It used Diameter-based interfaces internally to communicate with MME, HSS, and PCRF, which were complex to extend. The T8 API surface was relatively narrow, focused primarily on IoT use cases rather than the broad programmability operators envisioned…