When I call the phone number back it says thanks for calling Delta Telecom Services - I don't know this company and have not called them before. Although it says 08 as the area code, it says the number it from White Cliffs, NSW on my iPhone details of the call. I don't even know if this would be scam or unsolicited marketing.

Claimed to be from Visa and Mastercard administration and advised a suspicious transaction on my cad of $800+. Says to press 1 to speak to an investigator if I believe it is an unauthorised payment. Doesn’t address me by name, doesn’t identify which card, Visa or M’card, obvious scam. Blocked.

Caller: SCAM

Received scam robo-calls pretending to be from "Olivia of the Commonwealth Bank", two calls in two days from different numbers, about supposed "payments of $1800 from your debit card". I have not made any such payments. Hung up.

Caller: Delta Telecom Services

Has call twice within 2 minutes. No message left. Have blocked the number.