I have one of those slinky-Kate. Worked super for a time but blocked list fills up quick.can only hold 10 numbers. At first I blocked all foreign and withheld numbers. But eventually realised I was missing doctors phone calls so reluctantly had to allow withheld numbers. I have started to receive nuisance calls again. I'm going to look into emptying blocked list if I can and start again.
Worst caller is TalkTalk. Telling me my computer or router is faulty.