You can check a few things.
First check if do not disturb or another focus is on:
- Do Not Disturb:
- Swipe down from the top right of your screen to open the Control Center. Tap the Focus icon (moon) to disable Do Not Disturb, or any other Focus mode that might be active.
- Focus Modes:
- Go to Settings > Focus and ensure that any active Focus modes (like Driving) are turned off or configured to allow calls from the person calling you.
2. Check Silent Mode:
- Silent Switch: Locate the Ring/Silent switch on the side of your iPhone. Ensure it's not in the "silent" position (orange showing).
- Action Button: For iPhone 15 Pro and later, the Action button can also toggle Silent mode.
Verify Call Forwarding:
- Settings: Go to Settings > Phone > Call Forwarding. If it's enabled, turn it off.
4. Check for Blocked Numbers:
- Settings: Go to Settings > Phone > Blocked Contacts. If the person calling is blocked, remove them from the list.
5. Check If silence unknown callers is on
- Settings: Go to Settings > Phone > Silence Unknown Callers. If enabled, calls from numbers not in your contacts will go straight to voicemail.
6. Check your cellular signal
- Airplane Mode: Turn Airplane mode on, wait a minute, and then turn it off. This can reset your network connection.
- Check Signal: Ensure you have a good cellular signal.