Sounds like a debt collector to me

I never give out numbers or confirm identity on calls that are unsolicited. I either ignore them or get a number and call back

We always pay our bills on time however when we built our house this year the builder opened an account in our name for the electricity while the building was underway. However they did not give the company our correct address and so I had multiple calls asking me to return a call to a 1300 number. I ingored it for months thinking it was a scam. One day I finally called them back and it was for the electricity account we never recieved!!!!

Good luck