Joe's mobile phone isn't very loud. What can he do? Leo says that each mobile model is different. Some are even too loud. But there is a known issue with low volume during calls with the Moto G5. There's also a setting called "voice privacy" that he can disable to turn it up, and under Accessibility, there is a "hard of hearing" setting. He can get another 25% volume by turning up the volume all the way and while he's holding the volume up button, press "OK" on the excessive volume warning screen.