Cellular option is NOT accessible

Hi minwyng,

Thanks for contacting Apple Support Communities!

We understand that you're unable to connect your cellular network because your SIM card isn't recognized, correct?

If so, check out the troubleshooting steps outlined here to help you to connect to your cellular network: If you see 'invalid SIM' or 'no SIM' on your iPhone or iPad - Apple Support

"If you get an alert that says Invalid SIM or No SIM Card installed, follow these steps.

1. Make sure that you have an active plan with your wireless carrier. 
2. Restart your iPhone or iPad.
3. Check for a carrier settings update. Go to Settings > General > About. If an update is available, you'll see a prompt to select OK or Update.
4. Remove your iPhone SIM card or iPad SIM card from the SIM card tray and then put the SIM card back. Make sure that the SIM tray closes completely and isn’t loose. If you use a SIM tray from a different model iPhone, iPad, or from another phone manufacturer, it might not fit properly.
5. Try using another SIM card. If you don't have one, go to your carrier's retail store and ask them to test with another SIM card. You might need to replace your SIM card.

If you still see an alert about your SIM card, contact Apple support.

Learn what to do if you see a SIM not supported alert."

We hope this helps.

Take care!