How do I block a phone number that is spam/****??

Only your cellular provider can block a phone number, so give them a call.

Number blocking is done by the cellular carrier and not on the iPhone. Verizon has an app and a website where you can log into your account and block a number. Check with your carrier.

If your carrier does not offer call blocking...not all do & those that do generally charge for this feature...put the number in your contacts list & assign a silent ringtone to it. The call will still come through, but your phone won't ring. That's what I do.