Dealing with Unwanted Calls
If you receive inappropriate calls you should report them to the police on 101 or to your phone provider.
Calls should be reported even if the caller is on a withheld number (the number can be accessed by your phone provider).
Smartphones are capable of being put in do not disturb mode which can be easily configured with exceptions to only allow calls from your favorite contacts. Do not disturb mode can be set to automatically come on over night.
You can also set your phone to block withheld numbers.
These features are also available on some home phones eg Gigaset C430a
How to set do not disturb mode on: