blocking is not possible? i can block most numbers (authorities are n exception).
spam calls are always from random numbers so it usually doesn't do anything. They're almost always spoofed numbers too, meaning the number it tells you you're getting a call from isn't actually the number calling you.
If you answer a random number and it's clearly a scam, you can hang up and call the number back and a different person will answer having no idea what you're talking about because it wasn't actually them calling you.