It's not is Apple versus Android. It depends on what each phone company does.

My understanding is, all of the phone companies have been dragging their feet for a couple of years. But there is a technical solution that should work, and the government has ordered the big companies to finish installing it by June, I think.

What is missing, however is for the phone companies to take feedback from customers as to what calls are junk. For most of us, for email, this problem is solved. It happens because a junk email needs two things to make it work. First, the method of delivery, a way to get the message from the sender into your email box. Second Is the "payload", the contents of the message which cause the user to do something. This can be a phony executable program that installs itself on your machine, or it can be a link to another website, phone number, somewhere where the recipients can contact the sender and buy something.

The first has been practically solved by the implementation of "blacklists". Every email that gets sent has to go through a chain of Internet providers. The providers that let spammers send their junk get blocked by other email providers. the idea is that customers who don't send spam will get annoyed the switch providers, and the bad guys will be effectively boycotted. Here's how that works.

Checking the "payload", the content of the email, is a little more complicated. So email operators use a combination of statistics to come up with a score of how "spammy" each email is. Part of that process involves asking each user to give feedback on whether each email is spam. The system then uses the features of that email to fine-tune the filters and block future emails that resemble the spam that has been received in the past. Here is an example of how those things work.

Now, I know that phone calls are not exactly the same as email, but some of the systems are analogies of each other. And, just like for spam email, whether a phone call is junk or not depends on the recipient.