iPhone 8 is ringing randomly on when my ringer is on

before my iPhone 8, I had a iPhone 6s, and whenever I had my ringer on, it would just randomly ring. No one is calling me, no reminders are set, no notifications, nothing. So I’m getting really confused to why it’s randomly ringing. My iPhone 8 is now doing it. (It’s the same SIM card) I never downloaded anything that I think could have a virus linked to it, but I’m just tired of it ringing randomly.