Caller: Didn't speak a word of English

This person I spoke with was speaking Chinese or Cantonese. I am not sure if it was a computer-generated voice. Every time I tried to talk the just kept talking. I hung up and called the number back straight away. Only to be told that this number has been disconnected. How is this allowed to happen? I get these calls over and over and over again each week. I just keep blocking them. Still, they call. I have even answered them and no one speaks but I can hear people in the background.