I am getting these calls too... they are actually for Ron Paul running in the US Election... they are calling customers also who use VoIP Services...

Our business got another call from 956-421-1006.  Always the same, a hangup when I say hello.  Very annoying.  They interrupt my work to play these phone games.

Got a call from 956-421-1006 at 10:38pm EST. No response.  When you call back you can hear their auto-dialer at work calling other numbers.

Whoever is responsible for this operation is the scum of the earth.

Got a call at 9:30 am eastern time. No one on the other end. My smart phone IDs the number as "Harlingen, TX". They called on my 800 line.

(956) 421-1006 calls my 800 number several times a week. Nobody ever there and always a busy signal if you call it back. Very irritating!  All I can find out is that is is from Harlingen, TX and is Unpublished or Unavailable as to has the phone line. You would think the phone company in that area could do something to stop this.

I get a call from them every week and they never leave message .

3:42am........weird.

I got a call from this number at 3:25 AM - left no message.  Caller ID said 800 Registry Co

same . got a call no hello

Number called at 10:50 pm.  no response to my hello.