they call, I answer, they don't talk and hang up. great convo!

they have called repeatedly with numbers ranging from (02) 8046 6504 through to 6519, whenever I see any number in that range now my old referees whistle comes into play - havent had a call for 3 days now !!!!!!!!!!

Rang it back - bit of music and then the call ends. This also has a few other numbers they use (02) 8046 6521

When my answering machine message concludes the caller hangs up. I also get these calls from (02) 8046 6516.
I do not know who they are but if they do not leave a name/number I conclude that they are spam calls. I only answer calls for which I have ID's as my number attracts a lot of spam calls for some unknown reason.