A call from this Anaheim VOIP number arrived today.  When the call rolled to voice mail, the caller left no message, just dead space.  This is typical of robocallers (unlawful telemarketers) who use automated dialers to troll the phone lines seeking to spam gullible victims.  That may or may not be the case in this instance, but it validates the wisdom of letting the answering machine take calls from unfamiliar numbers.