Calls and says "goodbye"

It sounded like a scam. They said that they are shutting down my internet conne tion tomorrow, because there are too many errors on our line.

Some Indian indicating my telstra internet is going to be cut off and that if the Nazi's had won, that I would be calling him sir, instead of bootlicker, which I did not. Bootlicker is solely reserved for official telstra representatives.

They did not say anything when I answered call. Tried to call back, however not able to call this number. Obviously a scam or nuisance caller.

Some Indian ferret called and said he was from Telstra and he needed to talk to me about my internet connection. As soon as I told him I didn't use Tesltra for internet he hung up !

Said he was from Telstra and that my internet connection was going to be disconnected for 4 weeks due to someone using my internet from an IP address etc etc and I didn't know it. I asked for his Telstra ID and he said "can't give it to you over the phone" I told him I didn't believe him and I hung up. I called Telstra and they confirmed this tel number is NOT from their call center and to let them know if I get any more calls from this number.

Same as Kim experienced. Indian guy from "Telstra" informing me my internet would be shut down today due to hacking tools that were mysteriously downloaded to my PC and "Line errors'. As soon as i replied "Sounds like BS to me mate", he hung up. HA!!.
He would have had more luck asking for pics of "Bobs and Vagene"

Same as Kim experienced. "Telstra" informing me of line errors due to hacking tools that have been downloaded mysteriously onto my PC, therefore my internet will be shut down today. as soon as i replied, "Sounds like bullsh*t to me mate' he hung up.. This is a known scam to gain remote access to your PC and thereby get your banking details.
He would have had more luck asking for pics of 'Bobs and Vagene"

Same as Anon on 9 Jan 2018. Calls, says "goodbye" then hangs up.

How do i find out if these are legitimate calls or not

called and said 'goodbye'.