This number called me regarding a non existent motor accident that I was supposedly involved in. I told them off and hung up. When I tried to call the number back to unleash my frustration, I was prompted with a message. "Optus would like to advise this mobile number has been disconnected". Seems very suss to me so don't provide any personal details to such phone calls that you recieve. Try asking them to provide details like your registration number or license number. If they don't know then how did they get your number.