Caller: Another call saying from Telstra Technical Dept

My computer causing problems on my Telstra internet connection. 2 calls from this number on 28/9/18 and 29/11/18. I have never had a Telstra internet service. Phoned that number today - not connected.

This number called me twice yesterday afternoon without leaving a message and has just called me a third time. When I answered, I got silence and then a recorded "Goodbye". Stupid pests.