If your calls keep dropping suddenly when you hear a click sound, it could mean that your iPhone has a default setting enabled to end calls when the side (right) button is pressed.
To change this setting, navigate to:
Settings > Accessibility > Touch
Enable the “Prevent Lock to End Call” setting.
This setting will stop the right hand side button on the iPhone from ending a call, which is a terribly enjoying feature and one setting that should be changed as soon as possible.
The amount of phone calls I had when the call ended abruptly by accidentally touching this button were too many to count.
