When you use SightCall or Visual Support app for the first time, Android will prompt a window asking if you would allow the app to have access to the microphone and camera. Sometimes, this prompt window can disappear quickly or the user may accidentally tap the wrong area on phone screen that causes the prompt window to disappear and the app ends up not having access to mic and camera.
In such scenario, you can apply the following steps to make sure SightCall or Visual Support app has all the access needed:
1. From the Android main menu, swipe from the top to the middle of the screen and click the Gear icon.
2. Select Apps >> SightCall.
3. Scroll down and select Permissions.
4. Enable access to Camera and Microphone.