Galaxy Note 9: How to install the SIM card in the device?
With dual SIM model, Place the primary SIM or USIM card on the SIM card tray 1 and the secondary SIM or USIM card on the SIM card tray
Use caution not to insert the SIM card on position for memory card. Doing so can cause damage to the SIM card or device.
If the card is not fixed firmly into the tray, the SIM card may leave or fall out of the tray.
• If you insert the tray into your device while the tray is wet, your device may be damaged. Always make sure the tray is dry.
• Fully insert the tray into the tray slot to prevent liquid from entering your device.