The number you have dialed is not a working number?

[EZPKNS34]

I called someone and instead of it ringing, I got the following message:
"The number you have dialed is not a working number. Please hang up & try your call again."

Does this mean the person hasn't paid their bill? Or does it mean they have changed their number or service?

They have (or had) cingular if that matters.
disconnected meaning they didn't pay?

 

[Unregistered]

the number you called isn't a working number

I hear the same message when I call from a cell. When I call from landline I am able to call the person.
Weird.