How to increase ambient sound and avoid posteriori by calling posteriori?

1. First, turn on the phone and click the call button. Find the phone records, because I just called my mother, and she was very noisy there, so I had to hang up and call again. Find the dialed number or set it directly. Find the phone just now, click it, you can redial and delete it, and there are settings. Click more at the back to set it.

2. Click Settings, I want to find a way to solve the noise problem. Open the settings, there really is, slide to the bottom, look, it's gray to eliminate the environmental noise during the call, let's set it up. Just click on the gray to turn blue, and this function has been turned on.