Sign up on the DoNotCall register.
It will stop the honest ones from calling and when the dishonest ones do call, ask them for their business name and ABN and they disconnect very quickly.
It doesn’t make you immune to Political or Charity cold-calls, but if you mention that you will never vote or donate to someone who does cold calls, you get out on their internal DNC list very quickly.
It also doesn’t stop Scam/Illegal spam calls, but if you ask for their legal business name and ABN enough times, they soon get the picture and will disconnect the call.