Hi!
Here are some possible solutions you could try:
1) Check your Calls: Check if you have set up any options that might affect your call behavior. Go to Settings > Phone > Calls and check settings such as "Call forwarding", "Caller ID blocking" or "Block calls".
2) Restart iPhone: Try to restart your iPhone completely. Press and hold the power on/off button until the red power bar appears, then swipe to turn off the device. After your iPhone turns off completely, press and hold the power on/off button again until you see the Apple logo.
3) Update software: Make sure you have the latest version of iOS software installed on your iPhone. Go to Settings > General > Software Update to check for updates.
4) Reset network settings: Go to Settings > General > Reset and select "Reset network settings". This will erase all your network settings, including the associated Wi-Fi and Bluetooth devices, so you’ll need to reconnect to Wi-Fi networks.
5) Contact Apple Support: If the problem persists despite troubleshooting attempts, you may want to contact Apple Support for further assistance. They can provide you with specific solutions to your problem.
I hope I helped you!