my iphone 6 can not make or receive phone calls it just freezes how can i fix it?

Hi moraless___,

Thanks for using the Apple Support Communities!

I understand that you are not able to make or receive phone calls on your iPhone because it becomes unresponsive. Is this the only feature that does not work as expected?

I see that you have already tried restarting your iPhone and reseating the SIM card, but the issue continues. To continue troubleshooting, there are a couple of steps I would recommend.

First, close the Phone application completely.

Force an app to close in iOS - Apple Support

Once Phone has been closed, restart your iPhone again as you did previously.

Restart your iPhone, iPad, or iPod touch - Apple Support

If the issue continues after these steps, please let us know so we can continue helping you troubleshoot and resolve this issue.

Best!

Thank you for replying. Because the previous steps didn’t help to resolve the situation, the next step I would like you to complete is reinstalling iOS on your iPhone.

Reinstalling the iPhone Operating System should not affect any of your data, but it is always a good practice to make sure you have a current backup of your devices.

iPhone - Backup - Apple Support

Once your iPhone has been backed up, follow the instructions in the next article to reinstall iOS on your iPhone. After the reinstall finishes, test the issue.

1. Connect your device to a computer and open iTunes. If you don't have a computer, you can borrow one, or go to an Apple Retail Store or Apple Authorized Service Provider for help.
2. While your device is connected, force it to restart. Press and hold the Sleep/Wake and Home buttons at the same time. Don't release when you see the Apple logo. Keep holding until you see the Recovery mode screen.
   
3. When you get the option to restore or update, choose Update. iTunes will try to reinstall iOS without erasing your data.
   

iTunes will download the software for your device. If it takes more than 15 minutes, your device will exit recovery mode and you'll need to repeat steps 2 and 3 again.

If your iPhone, iPad, or iPod touch doesn't respond or won't turn on - Apple Support

Best!

Thanks for replying again.

At this point in troubleshooting, it may be more beneficial for you to contact AppleCare directly. Contacting Apple Support will allow us to look into this specific situation further so we can offer you the best support possible.

Contact Apple Support - Apple Support

Best