Caller: Phantom number

This number called me. I did a few things that flagged it as being suspicious
1- When I called it back Telstra said it could not be connected
2- no message left
3- no such number exists.
4- a investigation into overseas telemarketers mainly in India have noted that telemarketers have identified that most targeted people look for certain giveaway hallmarks of a telemarketer. One being a hidden number. Their new software generates s number to show the target that makes the target believe its a local call. But if it’s not answered and the target returns the call. They will find that the number can not be connected.
Be smart. Don’t answer numbers you don’t recognise. You can always call them back.