If you believe your phone is not getting the best signal possible, you can “kick it” and force it to re-acquire its cell signal. This is like hanging up from a phone call with a bad connection. Then call back and you’ll most likely get a better connection. Not always, but often.
You could reboot the whole phone, but it’s quicker to just reset the cellular connection:

1. Turn on airplane mode – that “hangs up” – turns off all radios
2. Turn Off airplane mode – that turns on the radios and forces it to re-acquire the cell signal

Watch this 1 minute video to see exactly what we mean.