Hi there!
Welcome to Apple Support Communities. We understand that you're having an issue with incoming calls on your iPhone. We'd like to help to make sure you can still hear from your father and other important contacts.
Are you having issues with the alerts tones for things like messages that come in? How about playing music on your device? Do the speakers sound as expected? If you go to Settings > Sounds & Haptics, can you hear sounds if you move the toggle below Ringer and Alerts?
Do you have Do Not Disturb enabled or Focus scheduled? These features can affect the way incoming calls arrive. Check out this resource to see if it helps: Use Focus on your iPhone, iPad, or iPod touch - Apple Support
Turn on Focus
1. Go to Settings > Focus.
2. Tap a provided Focus option — like Do Not Disturb, Personal, or Sleep — then turn on the Focus.
3. After you choose a Focus, select options like Allowed Notifications, Time Sensitive Notifications, and Focus Status.
Let us know if you can find any setting that may be affecting the incoming calls through Focus.
Take care!