SIM related issues may include one or several of the phenomena listed below:

Cannot read SIM card

1. Remove the SIM card to check if SIM card has any damages or is wrongly inserted. 

2. Cross-check if the same SIM card can be used in other devices or try a different SIM card. 

3. Open "Setting"->"SIM & Network setting" -"SIM Settings" to check whether one of the cards is deactivated. If yes, please activate it.

4. Change to another SIM card. 

If this issue only occurs when using a single SIM card, contact the network operator for a SIM replacement. 

If the issue persists even after trying more than two different SIM cards, please contact OnePlus for after-sales support.