Iphone12 makes random calls on its own

My husbands iPhone has been making random calls without any human help. Calls that are not related to a previous call, incoming or outgoing. Not related to recent messages sent or received. Literally random. Eg his phone called me while he was asleep- the phone was situated on a table away from him. He was only aware of the “rogue” call when I called him back. Other instances have been while he has been driving (he doesn’t ever use his phone while driving) one time his car had been locked in the car & made calls to people he rarely speaks to by phone, including my sister who was overseas) and at times that are completely inappropriate due to the lateness at night. We have tried all the previous suggestions and nothing works. Anyone have a new idea?

thank you DG