Just got a call from this number no one spoke then recorded voice said "goodbye" and hung up.

'Telstra' calling about the illegal activity I have happening through my BigPond account, told me my service would be suspended for around 30 days from tomorrow. Called the number back, and music playing as if on hold.

This number has called both my mobile & landline, claiming to be BigPond, suspending my account tomorrow for a period of 25-35 days, due to the illegal activity that is happening through my account. Told her I was busy, asked if I could have a number to call her back. She said that was fine, she will call me back, and hung up.
Called back this number, and get 'on hold' music.