Migration path: NSA → SA

A Phased Migration Approach

Migrating from NSA to SA is a multi-phase journey rather than a single cutover event. In Phase 1 the operator deploys a 5G Core alongside the existing EPC and begins serving SA-capable devices on the new core. Phase 2 establishes interworking between the EPC and the 5GC using the N26 interface that connects the AMF to the MME, enabling seamless mobility as subscribers move between 4G and 5G coverage. Phase 3 gradually shifts traffic onto SA, and once coverage parity is achieved the operator begins decommissioning the NSA anchors and eventually sunsetting the EPC entirely.