Caller: Someone claiming to be from Telstra

I received a call from a male person claiming to be from Telstra wanting to warn me that my device may have been infected with a virus. He couldn't tell me any of my details, not even my name. The call came through my silent landline number. I had actually sent an SMS to Telstra on Monday regarding a fault with my internet. I called the number back on three occasions and all three times the call dropped out before connecting.