Aussie here, I get the odd one on mobile, but get a couple a week on my land line numbers. Land line numbers are also registered with Do Not Call, but doesn't

Aussie here, I get the odd one on mobile, but get a couple a week on my land line numbers. Land line numbers are also registered with Do Not Call, but doesn't make any difference. Answer the call and there will be either: 1) a few second pause and then a person will drop in with the call centre voice noise in the background. 2) a few second pause and if there is no sound (you saying "hello") it will hang up. Those are usually from international call centres. In terms of locally based ones, got a couple during the election with a recorded voice saying "this is an important message from XYZ politician".