Hello BJTJ1994,
Thank you for contacting Apple Support Community! I see you are having issues with your iPhone not ringing every time you receive a call, it is important to be able to receive notifications for all your incoming calls.
First, check under Settings > Phone, there is an option that says Silence Unknown Callers, make sure it's turned off as it will not give you any notifications for anyone that is not in your contact list.
Also, check this article that shows guidelines for notifications settings on your iPhone, Change notification settings on iPhone.
And finally make sure that the iPhone is on the latest software update, Update your iPhone, iPad, or iPod touch.
Take Care!