Repeated calls not leaving message, call back and the number is always engaged. Call centre?, scammer?, auotdialler?

An automated message claiming to be calling about my visa/Mastercard.

had a few from 03 numbers in past few days asking about if im the one that pays power bill then hangs up

Definitely a scam call.

Caller: Not Optus

Automated messaged purportedly from Optus saying "Your service will soon stop working".
I have no services with Optus.

Caller: Peter

Scam. Fraud.

Caller: Visa

Husband took automated voice message about his Visa card being debited an amount, it okay press 2 to dispute press 1, he hung up

I got the same today, from visa/mastercard saying that there is a transaction of $1299 and if I want to approve it to press 1

Called and hung up. Obviously scam call. I don't answer unknown numbers, usually suspecting scammers are calling.

Caller: Amazon Iphone calls

Scam call, wanted my home details to send me the iphone from Amazon. I told her to stop being a scammer and she started humming a tune - accent from India.

He/she waited a bit then hung up. I have blocked the number.

My Telstrs phone identified call as a Scam.

Caller: Scam

Claimed to be from Telstra telling me that my I.P. address has been hacked and is being used by foreign people. Wanted me to down load a program to give remote access to my p.c. Became argumentative when I refused.

Caller: Scam

Call and say they’re from the NBN. They hung up as soon as I said I knew it was a scam

Caller: Spam

They call then hang up. The number is not connected when I redial