If you are with BT, and you have the 1571 voicemail service, then by now you should have been given the (free) 1572 Call Protect service. It was due to be rolled out by 31/03 but ours went live around the middle of this month ....
As I understand it: (a) BT has a list of numbers used by scammers and will automatically block them and (b) you can add your own numbers onto a personalised list. If anyone calls from these numbers, your phone won't ring, it'll go straight to a 1572 junk voicemail box where they can leave a message if they want. When you check your 1571 voicemail, it tells you if there's anything in the 1572 one.
You can also (a) block any incoming international calls, (b) block any calls where the number is withheld and (c) block any calls where the number is unrecognised - but you have to turn these three options "on". I have done so, because we've had a spate of spoof / scam calls from withheld numbers recently, but I'm wondering if genuine organisations (NHS, local government etc.) might phone you from "withheld numbers" .....
Has anyon else got 1572, and if so, how have you configured yours?