Open5GS Made the EPC Feel Like a Set of Services Instead of One Big Core
Breaking the EPC into MME, HSS, SGW, PGW and PCRF roles made LTE core traffic much easier to follow in captures and logs.
MME
The S6a Interface Connected LTE Authentication to the HSS for Me
Tracing S6a made the HSS feel less like a subscriber database and more like an active control-plane participant in LTE attach and mobility.