My local hospital telephones with private numbers, which is the only reason I cannot completely block them and thus cannot use a whitelist. Outside of working hours I do not answer them. I told them it is a problem and they placed a note in my record to call me from a public phone which is nice of them (not their own desk but from a service desk which has a number displayed) but I imagine they sadly sometimes forget.
The UK number is a hassle too, all kinds of +44 numbers spoofing or reusing existing non-fixed location numbers to seem legitimate since some phones provide direct listing of the name of the company. They are actually foreign redirects which cost insane amounts of money if you call them back.
I would also like a native way of blacklisting number blocks (like +44), my phone currently can't unfortunately.