Caller alleged to be from the Commonwealth Bank and was ringing about an unusual transaction that occurred approximately 20 minutes earlier. Had received a similar call from a No Number ID approximately 2 weeks prior and was suspicious then and said I would hang up and call the bank myself. Confirmed with the bank then that the call was a scam so knew on the second occasion that it again was a scam. Told caller this and hung up. On both occasions, caller had what sounded like an American accent. There was also a slight delay when I answered the call which always makes me suspicious.