I was suspicious too but I called Telstra and have confirmed that this is a Telstra number.

Oh ,they called me and left message , say " ... we require very important information from u , please call back Telstra at 132210 . " a very unclear connection.

No response.

Just got a call from this number to my current telstra mobile number which I've only had less than 6 months.  They asked for me by my maiden name which I haven't used in 9 years so I declined the call.

I called Telstra myself and asked about the number. Due to restrictions imposed upon them they could not search the number. The guy I spoke to said that the number normally would come up as private and not a visible number. He also said that he did not believe it was Telstra and encouraged me to report it to the police. This is exactly what I am going to do. My advice is DO NOT give personal details the them. If you are unsure then call Telstra yourself and confirm everything with them.

I declined the call because I don't recognise the number; they've called several times in past few days. I saw the posts here - what is Telstra RTS section?

I was called - identified to be from Telstra - RTS section

I can confirm Telstra, or at least someone who pretended to be them…