Caller: Scammers!?

This mobile number called me today at 5.06pm. I answered it and got an Indian male calling himself Mac and identifying himself as Telstra. I told him Oh great, just what I need another friggen scammer and told him to go get a life and stop ripping people off and hung up on him. Later I told the Hubby what had happened and said usually you cant call their numbers back because they are almost always immediately disconnected. He said to try it. I took my show caller ID off and rang it back and got an Australian male from a software company who denied any knowledge of it and stated this was his number. Not sure if hes in on it or whether they are finding a way to use other peoples numbers without their knowledge.