a very similar number to the serial pests responsible for (02) 8323 4300

I have received multiple phone calls (every day) from this and similar numbers in recent weeks from numbers that all appear to be from NSW.

I have answered a few calls and there is no one there, and if I return the call the auto message says 'the number you have called is not connected'

Any one have any idea what these nuisance calls are about? And if it is a scam how does it work?