They phone and don't say anything. I can hear voices in the background and then they hang up. This has happened two days in a row.

They phone then hang up. You can hear background noises. When you call the number automated voice says "Your call could not be connected, please check the number and dial again." Happens a lot lately.

Supposedly a company representing Telstra who want to give a 30% discount on our bill. We told them to email the offer to us and that, if they really are from Telstra, they'll have our email.

This number calls and says nothing then hangs up.