What to do about this blocked number?

For the past 3 hours, I have gotten a call from "blocked" on my iPhone. I only answered once and the other person on the line keeps asking me if I had any illegal drugs which I don't and I responded saying that this guy has the wrong number over and over but he didn't want to believe me and yet he asks me the same question only for him to get in a angry rage and using all sorts of strong verbal language before I hung the phone up. Now he's still trying to call me but I refuse to answer. Should I get my number change or call the police with the times of when this "blocked" number called me? I went thru my recent calls and written down all the times that this guy has called me.

Added (1). Also, I can't block this number because it comes up hidden and it only shows "Blocked" as there's no 10 digit number whatsoever.

Contact both your service provider and the police.

Can't you block blocked numbers?

Contact your wireless carrier and ask if a feature is available where you can refuse to accept calls from blocked numbers. If a feature is available, a person can't call you unless they unblock their number. If you can't get that feature there might not be anything you can do. The police probably won't be able to do anything either.

Call the police. Make a report. They can trace the call when he calls and deal with him. Call your carrier, a necessary step… The equivalent of calling the phone company, and tell them what is happening and that you want to block him and for them to give the info to the police.