I rang back a few times before I got through but it is Telstra Business Centre.

I keep getting calls from this number but there is no answer when I pick up the phone. Who is it??

Multiple calls over the last few weeks. When I pick up there is just a beep and then hangs up

This is Telstra in Bendigo and they have become a real serial pest. I answered one day not knowing who it was, when I found out I told them it wasn't a good time. EVERYDAY since they call me and have even started twice a day. This has been going on for weeks. I just let it ring out and they don't leave a message. Surely they have to give up one day?

This is a Telstra Business Centre in Bendigo conducting "Account Reviews". You cannot call them back to talk as it is a message service only and you cannot even leave a message.
Interestingly, I have asked them >6 months ago to remove me from any telemarketing but I guess as they call it an account review, it will be interesting to see what they say when next they call and I answer,

I've also been getting calls from this number and it immediately hangs up on me.

Missed calls from this number, always hang up

Telstra business centre