Voice on calls are too quiet

I got a new phone and sometimes it's hard to hear the person on the other line. Sometimes people say it's hard to hear me. This is a high end phone and I don't think this should be happening. What options are available to change? I've pressed the volume-up arrow to the top when I'm on a call and it's still too quiet. What exactly do the options: Speaker voice enhancement, equalizer and microphone noise suppression do?