Phone calls used to be such a quick, convenient way to talk or get info and uselessly governments have paved the way for scam companies to completely ruin the modern day phone call.
If I understand correctly you are just using the sim for data. Just forward the calls to a number that doesn't exist. That's what I did with my data sim. Worked well
You're likely to have been given a number which was previously used a fair amount. You could call your phone company and ask for a new number. At least that's how it works here.
In our country the national do not call registry is fake.
We are so smart that we gave the management of it to a "non profit" foundation that charges legal call centers millions of euros. It's 10000x cheaper to ignore the law and call people illegally from abroad. If get caught (very hard as numbers are spoofed, not illegal to spoof a number) pay the slap on the wrist and continue operating illegally
That bites, I didn't trust the US one. But I had a corporate number to test it on and so far these seem to be working. Carrion might work in your country but I think it is maintained by a US university. It blocks unsigned calls. Dont really know what that means but the spam stopped.
No idea, honestly. You might not be able to use them at the same time. I had to set Carrion to my "Caller ID & Spam Filter" app in the default app settings.