If Android does not detect a SIM card, the problem most probably lies with the SIM card itself or a hardware defect of the phone. But the causes of the fault can also be associated with the operating system especially if the issue arose after inappropriate rooting or updating Android.
Defective SIM Card
Make sure that your SIM card is in good order and ready for operation. Insert it into another phone (it does not have to be powered by Android). If the SIM card does not work with the other device, the possible reasons are as follows:
- Contacts contaminated or oxidized.
- The card is no longer serviced by the mobile service provider. If your SIM card has not been used for over 6 months and has not been topped up, provider might have deactivated it. It depends on the tariff plan you are using.
- An incorrect form factor or improper cutting (may be the case with older SIM cards without an adapter).
If your SIM card is damaged, it cannot be repaired. What can you do? If you are registered as the SIM card owner, all you have to do is come to your mobile service provider’s office and obtain a new SIM card with the same number.
Many service providers sell phones under their own trademarks. Those smartphones can work with the provider’s SIM cards only. If you insert another provider’s SIM card, it will not work. You will see an “Insert a SIM card” or “No SIM card” message.
This is also true for locked iPhones which users can buy at much lower prices in Europe and America. The price reduction is accounted for by an agreement with the mobile service providers that do not work in other countries.
Smartphone Related Problems
If your SIM card is in good order and your device is definitely not locked, you should look for a defect in your smartphone. The reason may be one of the following:
- SIM card slot damaged.
- Moisture or water damage.
- Mechanical damage caused by falling or impact.
- Software troubles after flashing, inappropriate routing or resetting.
If there is a hardware damage, contact a service center to fix the problem. Unqualified repair may aggravate the issue. As for a software failure, you can fix it yourself.
If your phone does not detect your SIM card and there is a “Check readiness” message, try to take the following steps (for dual SIM phones):
- Open the settings.
- Go to “SIM card settings”.
- Open “Standby mode settings”.
- Make sure that the SIM card is activated.
If a problem with SIM card detecting has arisen after improper flashing or an attempt of rooting, you have to reset or reflash the device. Let us see how Android can be reset to factory settings:
- Open the settings.
- Go to “Recovery and reset”.
- Press “Reset” and confirm the operation.
When a phone is reset, not only settings but also user data will be deleted. In order not to lose it permanently, make a back up copy before rolling back.