I'd had a call from a Thailand number (of course all these numbers have spoofed caller ID so it probably wasn't really even from Thailand) which I rejected after 1 ring. Then, seconds later, they tried on this number. This is fairly similar to mine with only a few digits changed. Out of curiosity I did answer but they hung up immediately, which tells me they were just testing to see IF I'd answer that number. So that was a mistake, it means now they'll keep trying from fake mobile numbers instead.
It's been easy for me to block all interstate and international landline numbers, and I wondered why they don't just simply use mobile numbers instead as people may be more likely to answer. So now they seem to have worked this out.
If you don't know, there is only one way to make the scam calls stop that actually works - you have to BLOCK them all. There is *nothing* you can say to them, no threats, no "take me off your list!", no "I know you're a scammer, you'll get nothing from me" or "I'm on the Do Not Call Register", none of that makes any difference. It's all totally automated, their computers make the calls and if someone answers THEN it connects you to a human, to save their time. This is why when you answer it's often silent for a few seconds, until someone takes over the call that you answered.
The only method that actually works is to block the calls. On most mobiles you can block all numbers that are not in your contacts list; this may require a 3rd-party call-blocker/dialler app, though rarely some phones have this feature built in. Another extremely useful feature is the ability to use wildcards; for instance, if you live in one state, you're not likely expecting many calls on a landline from other states. With the blocking app I use I can enter "(03)*" to block all numbers beginning with area code 03. Or more fine-grained, I could block "(03) 9079 00*" for a range of numbers I've seen the scammers use.
I've noticed when one number or whole range of numbers is blocked, they quickly change the fake caller-ID to another state. I can just imagine them desperately trying to outwit us... "Try a Melbourne number! Try an Adelaide one! Now Sydney... Busselton... Darwin... stupid rich whities are bound to fall for one of these!" When they finally realise you're blocking ALL strangers, they eventually do give up. And that is the only way to get it through to them that you're not worth their time. Even then, they WILL try again a week later, then the week after that, maybe just once a month, hoping you'll take the call filter off. But as soon as you see an obvious scam call just turn it back on for a week and they'll back off again. That's been the one way I've found that will convince them to finally give up on you.