An unwanted call from this invalid (obviously spoofed) number arrived today. When the answering machine picked up, the caller left no message, just dead space. Robocallers (unlawful telemarketers) do this all the time while trolling the phone lines seeking gullible schmucks to victimize.
Telecriminals (scam artists) spoof their numbers to avoid being apprehended by law enforcement -- all the more reason to LET YOUR ANSWERING MACHINE TAKE THEIR PATHETIC CALLS.