How to stop the robo calls

To silence unknown callers open settings and find phone, in phone tap silence unknown callers and turn on this option.

this will silence people and others who are not in your contacts.

Hope this helps.

Easiest? Mute all unrecognized numbers. Send’m all to voicemail.

There are tools in the app store which purport to reduce spam, though I’m somewhat skeptical as the callers—like email spammer that spoof sending addresses—will spoof calling numbers.

Your carrier might have some options here.

Let your legislative representatives know about hour concerns here, too.

You can do the following:

Open Phone App -> Recents -> [click on (i) behind the number -> Block this Caller.

The caller won't be able to call you anymore. It will not ring, and you won't see or know if they tried again. They are blocked. If they try, they won't know you blocked them, but their call will go to no man's land.

PS: I would not block an entire area code because you might be blocking legit callers. Usually, spam calls come from the same number or a block of about ten different ones.

Phone spammers don’t use the same calling telephone number, any more than email spammers will use the same sending address. If the spammers used consistent calling numbers or email sending addresses, their whole spamming business would immediately end.

Scammers want you to pick up, which is not achieved by always calling from a different number. So while blocking the number on your iPhone, they have no clue you are blocking them. My experience shows that they will try with another number after a while but soon give up and target someone easier.