Received call from this number 11:52am, said hello, got a hello back from a male voice and I said nothing in return. The caller didn't say anything but I could hear voices in the background faintly.

Received call from this number at 11.43am and upon answering I did not say a word and just listened and then after a few seconds it disconnected. I then rang the number back and ..... "Optus advised that the number you have rung has been disconnected." Then at 1.02pm I was rung by 08 5231 927 420 and because of the unusual looking number I did not answer and of course they did not leave a message. I called the number back and ..... "Your call could not be connected, please check the number and try again." My thoughts are that the first number is a computer dialing to check if my number is active and then a human rings from the other number which from this site tells us that it is a scam. How can they make calls and send these weird numbers as caller ID?