AFAIK they're not a problem here in Australia either, and the language here could (charitably) be called English. I've never received one of these calls.
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".