I'm on a spam call list and I receive phone calls frequently. Initially it was a +61 Oz number, so it was easy to block. But now they have switched to spoof NZ Mobile numbers.

The number is different every time. When I call back, I get a non-existing phone number error message.

I've contacted my provider, but they say it can only be reported when I'm called 5 times by that number.

Right now I've installed a call blocker that blocks all unknown numbers. It's a risk that I miss important calls, but I'm sick of the spam calls. Is there anything else I can do?

I believe this can be solved technically by the providers, by just not allowing to spoof invalid mobile numbers? Who can I report this too?