Prevent unwanted automatic phone call Before anyone tries to dismiss this question, I know of a identical thread, but that question is too specific about a certain behavior following a user interaction with the phone.

I am in search of a general explanation and solution!

The phone of my 11 yo child is a Huawei P8 Light, which made an automatic call, without any interaction beforehands. At 6 a.m. today my wife heard voices and thought she is crazy, but she could locate it. She picked it up, removed the loading cable and saw, that the child's phone called someone of the contact list!

My child cannot install anything without a technical permission (Google Family Link). Before I gave the phone to the child, it was wiped and reset by myself to factory settings. All updates are installed, including firmware updates.

What exactly does cause this behavior and how do I prevent it by some setting?

I do understand technical explanations (I am developer).
There is a far yet distinct possibility that this may be a screen touch issue. Does the phone open and close, etc. other apps too? If so, we may be dealing with a touch issue on the screen.

Another instance that I have experienced is: my friend had a phone that acted up random things when the phone was charging, meaning that when it was connected to a power source, be it a laptop or its original charger, the phone would do random things when on the table (without anyone touching it).

Also, as a third possibility, please perform a "clear cache" for the "phone" app in the "apps" list in your settings.