It is saying, they are from Telstra nbn!

this person's number has been ringing me all day. Nobody speaks, it seems to be a pre-caller for later scammer, they ring several times through the day then get the 'hi't comes later in the day. Probably to get a handle on the best hit time. If you ring it back it has a 'strange' answering machine message ' that says this is a 'private' number