This number calls my landline every day and more than once no message is ever left,
we are on a don't call register but they still keep calling whats the use, just go away.

I called back number (03) 8336 7684 rang 5 times then goes to busy tone.

The call is from Modern Group trying to sell you security door or one of their other product. The lady calling doesn't want to listen to you and only wanted to sell you stuff. Also even if you say no this time they'll call back in a few months time to do it again.

ring and don't leave messages, such a waste of their time and mine