Device doesn't recognize SIM card (USB dongle)

If the SIM card slot is clogged with dust, your device might not recognize the SIM card. You can clean the SIM card slot with a very thin toothpick or a needle, or you can vacuum out the dust using a small vacuum cleaner, with the suction power set to minimum.

If the SIM card slot is not clogged with dust, check out the other solutions.

Maybe the dongle "froze" and is unable to read the SIM card at the moment. All you need to do is to unplug it from the computer's USB port and plug it back in after a few seconds.

If the SIM card is not set in the correct direction, the device won't recognize it. Check the small illustration near the SIM card slot, or on the SIM card tray, on which the correct direction and (orientation) of the SIM card is shown.

If the gap between the contacts which read the SIM card and the holder (fixator) is bigger, the phone won't be able to read the SIM card. To fix this, you need to insert the SIM card first and then gently press the holder, using a flat screwdriver or another surface.

Maybe the dongle's computer driver is the real reason for the misbehaviour of the dongle and its inability to recognize the SIM card. If you tried restarting the dongle by disconnecting it from and reconnecting it to the computer, and it didn't work, try reinstalling the driver.

Maybe your device doesn't recognize the SIM card because the SIM card is damaged. To test this, insert another SIM card to the phone or dongle. If the other SIM card is recognized, replace the SIM card with a new one, but if it is not recognized, check the other solutions.

If the SIM card is dirty, your device won't be able to read it. Take a clean piece of cloth and pour some isopropyl alcohol. Then, clean the SIM card from the side of the chip (the "gold" part).

If the 3G/4G dongle is locked to a carrier, it won't recognize other SIM cards than the SIM card of the carrier it is locked to. Some dongles can be unlocked, and if yours is one of them, you can go to the carrier (operator) the dongle is locked to and ask their support staff to unlock it.

If one of the contacts of the SIM card reader is stuck, your device won't be able to read the SIM card. If the contacts are accessible, take a needle and unstuck the stuck contact. Be extremely gentle while performing the procedure, because you might damage (tear) the contact.

Installing the driver that comes with the USB dongle is a must, because of a good communication between the computer and the dongle. Install the driver either from the CD that came with the dongle, or through the dongle manufacturer's website.

Maybe the USB dongle is working fine and is able to recognize the SIM card, but the computer's USB port is dirty. If the computer's USB port is dirty, it won't be able to recognize the USB dongle.

Take a small piece of cotton and put some isopropyl (rubbing) alcohol on it and clean the USB port. You can also use a needle to remove dirt from USB ports but you need to be careful not to damage the connectors.

Maybe a buggy firmware is the reason behind this issue. Make sure to update the dongle's firmware all the time. You can look up and find instructions on how to update the dongle's firmware on the dongle manufacturer's website.