I can't make or receive calls on my mobile phone

Make sure you have good signal strength. You will find the signal bars in the top corner of your phone screen, and more bars means more signal.

• If you don't have much signal, try walking around to find a better position
• If you're inside a building, move towards a window

Check the SIM is correctly inserted. If your SIM is loose or inserted the wrong way round, your phone can't connect to the network.

• Remove your SIM card and rub the metal contacts to make sure they're clean
• Check that the cut corner of your SIM card lines up with the cut corner of your SIM tray
• Remove your SIM and turn the phone on. Then turn the phone off again, add your SIM and restart the phone

Turn off Flight/Aeroplane mode. If you've turned on Flight mode, you'll find that all wireless signals are disabled. This includes Wi-Fi, Bluetooth, NFC and your phone signal.

• For Android, go to Settings > Network & Internet > Airplane mode and make sure the switch is turned off
• For iPhone, go to Settings > Airplane Mode and check the switch is off

Try a different SIM in your phone. This will show you if the problem is with your SIM or your mobile phone.

• Try using your SIM in a different phone
• If you have a friend or family member with a mobile, try their SIM in your phone