iPhone XS Max rings on silent mode

I've been having this same problem for the past month, month and a half. Sometimes it happens, and it just rings even on silent, and the person is not a contact, so there's no Emergency Bypass setting to look at. Still happens even if I toggle the switch in silent mode.

Restarting seems to fix it, but it happens again after a while, and I haven't been able to track down what the trigger is.

What do you do if the contact who called is not a saved contact? I just experienced this problem and both callers were not saved contacts and were robocalls. It's embarrassing that my phone rings while on silent while I am at work, so looking for resolution ASAP. Thanks!

Check the contact record for the person that's ringing through. Go to the ringtone for that contact and check to see if you've turned on the emergency bypass. That will ring regardless of the mute switch setting or do not disturb status if you have.