If you use a third-party app to screen your calls (like Hiya, Truecaller, or RoboKiller), unblocking the number in your Android settings might not be enough. You must also open that specific app and remove the number from their block list, as these apps can intercept calls before your phone's native settings take over.
This method works for most Android devices, including Google Pixel, Motorola, Nokia, and phones running "stock" Android. how to unblock a number on android