How to block numbers not in contacts?

I don't know y but a lot of random people from all over the country have been calling me lately. And I never answer #s i don't know. Usually they just call once, sometimes 2 or 3
times but the calls r from many #s. And this happens once or twice a week.

and the prob is I carry my phone in my backpack and bring my backpack 2 class. And even tho the ringer is off and do not disturb is on, it still vibrates over and over. And it has happened in class twice. 2day was the 1st time the teacher noticed and said something. Luckily she didn't know it was me or at least didn't day anything. Not bringing my phone is not an option.

so anyways i don't know if it's even possible but can you block #s not in your contacts? If yes, how? If not, how do you block specific #s? Thts better than nothing. And I hav an iPhone btw.

You can download a phone number blocking app.

I haven't checked this, but I believe if you go into the phone menu in settings and scroll to the blocked numbers, you can type them in there.

I should also add: if you are leaving the phone in your backpack you can turn it off, nothing will get through to it.