Why does the network status of an NB-IoT module stay at 0x01?

(1) The power supply of the module is abnormal. (2) The SIM card is reversely inserted. (3) The corresponding service is not activated for the SIM card. (4) The firmware mode is consistent with the service activated for the SIM card. (5) The region is not covered by the NB-IoT network, which is the least possible cause. (6) The SIM card has been bound to a device before and cannot be bound to other devices. Contact the operator. PS_REG_DENIED is displayed in the logs if this is the cause. (7) The PSM mode is selected during product creation, and therefore, this mode is also used for the authorized module firmware. In this case, the use of the App is affected even if the PID is changed in the MCU, and you need to purchase a module in DRX mode.