Though it sounds like some of us take a slightly perverse pleasure from messing with these sods(yeah l used to as well), they are bloody annoying. So make use of the government's do not call service
https://www.donotcall.gov.au/consumers/register-your-numbers/ that should get rid of most of the australian buisness related ones, regardless of where they call from its the company they are selling for that gets in trouble if they call numbers on the do not call list. Some companies might call after this, but only if you already have a relationship with them(your a client) or you have at some point agreed to be contacted (lots of competitions, surveys, or charities).
The bigger issue is often freeking charities, l will never give money to any charity that calls me and l get pissed off with anyone that does give money to those sorts. Charities can be exempt from the do not call list, but must remove your contact if you tell them to. I'm generally pretty happy to donate to a good cause, but most major charities are just companies now where most of the money gets paid to admin, staff and commissions instead of the actual cause.
But the biggest single issue for me is around election time, because politicians can cold call as much as they like and will even use autodialers with prerecorded messages and normally from a local number.
As for banning calls from India, not quite that easy as most use a call system called VoIP that transfers calls via the internet to a local service that then makes it look like a domestic phone call. But these systems can certainly be regulated and given all true Australian phone numbers have to be registered to a person/buisness then there should be a register of these numbers as well. We should at least be given the option by our phone providers to block all of these types of calls.
I gave up on using a home phone years ago and only use my mobile now, it generally tells me if a call is likely spam so l just swipe it away. When they hooked up the NBN here it came with a home phone by default, but there has never been a phone connected to it, l wonder how many missed calls it's had?
