iPhone 16 not ringing for calls and will go straight to voicemail

You might have Do Not Disturb set to the on position. Here is how you can turn that feature on, or back off...

• Access Control Center:
• Swipe down from the top right corner of your Home Screen to access the Control Center.
• Locate the Focus Button:
• Look for the button that displays the crescent moon icon, which represents the Do Not Disturb Focus mode.
• Toggle Do Not Disturb:
• Tap the Focus button to turn Do Not Disturb on or off.
• Customize Do Not Disturb:
• To customize your Do Not Disturb settings or set schedules for periods of time, go to Settings>Focus> Do Not Disturb.

Have you tested it controlled like an experiment. You stand in a part of your house, have someone call you, see if it goes through?

check your carrier voicemail settings too. Old phones used to have call divert settings on voicemail and maybe the phone itself

I guess it's because of the setting of your phone; you might have accidentally switched it on maybe?