Caller identified as from Telstra. Said she was ringing about my Internet and to warn me that no matter how good my security was I could be hacked from Overseas. She would tell me what to do to stop this ...at that stage I hung up

Telstra do not call about possible disconnection of internet for maintenance reasons. They only send emails. Have checked with Telstra who confirm that this is a scam call.

Automated dialer I think.