What happens when a mobile phone that only supports the NSA network arrives in a place with only the SA network?

Solution:

 If bring a mobile phone that only supports NSA to a location that only provides the SA network, because cannot connect to the 5G network of SA, the mobile phone will not be able to use the 5G network, but will actively search for 4G, 3G, 2G network signals and connect at this time. For use. The SA standard was determined late, and the amount of construction work was large. It took a long time for operators to switch from 4G to 5G, and it took longer to switch to SA networks.