Hung up when I asked for Telstra ID and pointed out that Telstra IDs start with a letter.

Caller: I don't know

I leave some calls to stop. Then I ring back on another phone line. This means they haven't been able to register my main number as "live". This one is mildly clever. It then asks you to give your phone number so they can call back. I don't of course. Anyone calling back on my second phone number is immediately identifiable as a spammer or pollster as the line is only used for true emergencies and has no other incoming calls. You can also hide your number so they don't know who called. Mildly amusing. Second line is another carrier for when primary carrier fails in remote areas - dual sim phone. Telstra/Optus. Only needed once in 5 years but worth it on that occasion.

(03) 9962 2347 called at an odd hour. Didn't pick up. Robocall pattern.