What are phone calls that show up on caller id as 'unknown' and 000-000-0000?

Question

The name is 'unknown'. I know what that is. But the number is 000-000-0000. That is the confusing part. Also, no one answers me when I say hello. It seems to automatically disconnect after only a couple of seconds.

Answer 1

it's usually a blocked number when it's a telemarketer calling you & it's also usually a machine's voice too.

Answer 2

It is telemarketers or bill collectors!! They often have blocked numbers with zeros because they are calling from a call center. And since almost half of them are machine operated, it clicks, or hangs up, or takes about a minute to connect to hear the automated message.  My advice just don't answer!!