Our whole family of 5 + grandparents are on $10 pm plans from Belong which I understand is just a poverty pack Telstra, they certainly use the Telstra network. They are unlimited calls & text plus 1G of data that doesn't ever expire and can be transferred to any other Belong SIM. Some of us don't use much mobile data and transfer to those who need it. Obviously you can pay more for more monthly data if required.
