Lodge your complaint here

https://www.donotcall.gov.au/complaint1.cfm

I missed the call , I tried to ring it back but always engaged, suspect automated dialling.

I got a call from this number first, first no one there, then when called back it was apparently someone from Telstra calling about Foxtel and asked me for my name and DOB.  I asked about a password as usually they would do that, he didn't state my name, only asked for mine and he said cause of their new system no password so just hung up on him, not willing to provide any details.  I see on here now there's a bit of funny business from this #, my suspicions were probably right has nothing to do with Telstra or Foxtel.

I have just signed up with Optus - a brand new number which is only 3 days old and I am getting calls from this number also. Rules out Telstra unless they somehow have access to Optus's new mobile connections?

Of course they have access to Optus' data.  Optus rent almost all their infrastructure and network access from Telstra.

4 calls in the last couple of days. Including two today. Hangs up, never leaves a message. If I try call back I get 'Network Busy'