Callers like this is why my phone answering machine is used to screen calls and has outgoing message saying "You have reached xxx-xxx-xxxx. If it's worth calling, leave a message and I'll get back to you. If you don't think it worth leaving a message, why should I think it's worth answering the phone?"
Got a call from this number, and no one at the other end responded. Dialed the # back and the response was No one is available to respond to the Special Phone #.
2nd call this week (different #) to have similar situations.