We have to determine if the phone or the SIM card is the issue. Power your phone off, remove the SIM,inspect the SIM card’s gold plating to see if it is partially removed or shows signs of discoloration. Signs of discoloration or chipping of the gold plating means the SIM is damaged and needs to be replaced. If it looks normal, place your SIM in another phone to see if the same issue happen. If the issue occurs in both phones, that is another indication the SIM needs to be replaced. If the issue only happens in your phone, that means your phone is defective. Master reset your device and if that does not correct the issue, contact us so we can review your replacement options.