Undoubtly, we forget to turn our mobiles to silent sometimes. When it does ring in a meeting, I am frantically finding a way silence it.
The good news is that if you were to press the volume buttons located on the side of the iPhone, the ringing stops. However, you can't reject a call that way.
1st push of the ON/OFF button stops the ringing.
2nd push of the ON/OFF button will reject the call.