Started getting these calls this week.  A few different nos.  Called Telstra and was told it is a marketing firm and the calls are computer generated.  If an operator isn't available to speak to you when you answer , the call hangs up. You can call the DO NOT CALL REGISTER 1300 792 958 and select option 1.  Only problem, it takes 30 days to come into effect!!  I registered tonight. Hope this helps you and me.

Same thing happens too me, miss lots of calls from the same prefix 038664...., when i answer no one there, cant call back??? weird

Have had about four calls from similar numbers. They all disconnect when I pick them up and I cannot return the call. Who are they? Is it a scam that will charge me?

Cheers.
Getting these calls last few days from this number.I wont answer now.

I am pretty sure its a scam of some sort. It calls me too, hangs up when I answer and busy when I call back. I also get others with the same prefix of 866... I refuse to answer now and I hope it stops soon.

yes i have had this as well and when you call it back it is some strange computer generated voice saying it is being answered by audix or something for stephen someone.

not the first time i have had calls from this number