Solution:
The current 5G network will be similar to the initial 4G network model for a long time. Mobile phones only use the 5G network to carry data transmission, and they need to switch to 4G / 3G when receiving calls, sending and receiving text messages, and using certain carrier services. It is used under the / 2G network; the current 5G network is only used for data transmission, so when the dual card is used, only the "network card" can connect to the 5G network within the 5G signal range, and the non-network card cannot connect to the 5G network. When a 5G-capable mobile phone is used with dual cards, the data network card can be connected to a maximum of 5G network, and the non-network card (secondary card) can be connected to a maximum of 4G network.