Likely scammers.Tried calling the number but always engaged.

they hung up , this is not the only one we have one every day this week and our number is private.

first called at noon to speak about nbn. When told we didn't want to talk about it, hung up. Five hours later, called and hung up when phone lifted.

I live in country Victoria. On Wed 14 Feb 2018, a gentleman rang from this number concerned about my account with NAB (National Australia Bank). Although not identifying as "NAB security", his query to me was a security-type query. It concerned a (supposed) withdrawal of $800 dollars in the US which was a donation to a US health charity. Had I made such a withdrawal, he asked? No I hadn't, I replied, and what's more, I don't have a NAB account. At this, he hung up.

Claiming to be from Telstra in Melbourne calling from a NSW number immediately knew it was crap and said an old address I lived at 10 years ago