First time called my business...Picked up - no answer.  Called back and they are obviously calling from a pbx line where extensions are available...The extension that my call, called back on was unable to take any voice mails....Imagine that!  I think this must be telemarketers validating numbers...Further googling, here is what I have found....
"In some cases, it may actually put you on additional scam-bait lists, because the caller at least knows that it reached an active line owned by someone willing to pick up when an unfamiliar number calls."

Just got a call from this number, didn't answer it.  Agree with soph above.  The call from 404-856-6583 is bait.  If you answer it or call back, they may put you on a list of verified active numbers to be spammed and spammed and spammed again.

Been called repeatedly, this time after a long, long pause, a man said your business was referred to support Gays & Lesbian, something or another which was not true. . . Would I want to advertise the business in their  directory? I would never advertise a neutral b2b  business with this or any other radical activist type group, , very bad for business. , . Who cares who has sex with who should be private matter not associate a business brand with those issues.  Alternative sexuality  is getting insane and off putting to most. .

This number calls my cell daily how can we get this stopped

This number calls our office NUMEROUS times per day. When we answer nobody says anything. ANNOYING!!!!!!!!1