Is your iPhone giving you issues?
Basic troubleshooting steps that can resolve most of your issues with your iPhone is to reset the network settings! How do we do that?
->Go to Settings
->Go to General
->Go to Reset
->Choose Reset network settings
->Confirm

The screen will go black and you will see the apple icon. Your phone will reboot and Voila everything should be good to go!
Please make sure you configure your APN settings for Public Mobile after you have completed the above.
Cheers!