- Check that your SIM card is fully inserted.
- You should use only right type of SIM card in your phone, do not use SIM cards that have been modified to fit the SIM slot. You will have to contact your operator to order a replacement SIM card if a SIM transfer is not available at the retail point.
- Restart your phone.
- Your phone may be SIM locked, so using a SIM card from a different network operator is prohibited.
- Your SIM card may be damaged, and may need to be replaced. If possible, try your SIM card with another phone.
For more info, contact your network operator.