During a Video Call, I cannot see or hear my contact. The screen is black.

Check your internet connection. This occurs when one or more participants has a weak signal.

This issue occurs when the internet connection of one or both participants is weak. Common causes of weak internet connections are using the device in an isolated area of a building, such as a basement, or using the device outside of the building from where your internet connection (Wi-Fi) is being provided.   Try relocating to an area where the internet connection is more accessible to your device, such as open public areas of a building or closer to the internet router, if you can locate it.