Why isn’t my iPhone 15Pro ringing when calls come in???

Okay. It’s 3 1/2 years later. Now I have an iPhone 15Pro. No problems with text & message to tones. Now ny issue is my ohine doesn’t always ring at all or onky rings ince then it’s silent but call is still waiting for me ro answer. WTH Apple? Do you know how many important calls I’ve missed because my phone isn’t ringing out loud.