If your 4G router is unable to detect the SIM card or gets the error message “SIM card unavailable”:
Firstly please verify if the SIM card is inserted correctly.
Secondly please check if the SIM card is clean, especially on the golden contacts.
If there is dust/dirt/oil on the SIM card, you can follow the below tips to clean the SIM card.
- You can wipe the gold SIM card contacts gently with a soft cloth to remove any dust or oils.
- If unable to clean the specks of dirt, use a soft rubber pencil eraser to clean the gold SIM card contacts, and use a soft cloth to wipe away any eraser residue.
- The old SIM card might have oxidation on the golden contacts. You can use rubbing alcohol to remove oxidation. Dampen one end of a cotton swab with rubbing alcohol. Then gently rub the alcohol against the gold contacts on your SIM card. Continue cleaning the contacts until all of the oxidation is gone.