Non-Standalone (NSA)
Non-standalone 5G is a deployment in which 5G radio is added to an existing 4G network and relies on the 4G core and an LTE "anchor" for control.
What is Non-Standalone (NSA)?
NSA let operators launch 5G quickly by adding NR capacity to LTE sites while keeping the Evolved Packet Core. Devices connect to LTE for signalling and use 5G for extra data capacity. The drawback is that advanced 5G features, such as network slicing, are not available.