Non-Standalone 5G deploys NR radio alongside the existing LTE Evolved Packet Core without requiring a new 5G Core network. The LTE eNB serves as the master node while the 5G gNB operates as a secondary node. Together they form an EN-DC bearer, which stands for E-UTRAN NR Dual Connectivity, aggregating LTE and NR radio resources to boost throughput. All control plane signaling still flows through the eNB to the MME over the S1-MME interface. This approach enabled operators to launch 5G services rapidly using their existing core infrastructure.