They have called around 7 times today with silence on the other end

Same as above. Seem to be getting fax or dial up tone as well.

They sound like a call centre for sure, they've called me a number of times all saying the same thing as another number which I had blocked from calling me. Too suspicious. Ive asked not to be called again however a few hours later a new person.

I get repetitive calls from this number. Mostly no one on the other end. I have been told that some call centres use auto dialers and a free operator then picks up when they hear someone on the other end. When they eventually spoke it was to do with cheap call and internet rates with Telstra. It sounded like an Indian call centre. Could not make out the company name that was stated. None the less when an offer sounds to good to be true, it generally isn't. I got rid of him by telling him that o would have to call Telstra first.

Keeps calling and no one is at the other end.. Called possibly 5 times already today!!!

They have called me many times in the past week saying they are Telstra and saying they are putting my bill down after I give them my credit card details. I knew they were not Telstra because Telstra calls on a private number, and greets you by your name.
Just ring your service provider and report it to them like I did. :)

Received 3 calls today from this number - twice the caller hung up when I answered; third time there was just silence on the line.