Called twice no one on the line...

Received a call from this number to my business toll free number on January 23rd, 2010.  Lasted 1 minute but no message left.  Irks me because I have to pay the toll free call fee.  As above, must be a robotic caller.

We have an automated answering machine set up at work to capture information from prospects.  We received a call from this phone number, but no information was left.  The duration of the call was 9 minutes.  Obviously some type of robotic phone caller`

Called me on my personal business line Jan 24, 2010, seemed to hold for msg but no msg left.

called at 6.45 a.m. MST on Monday.  No-one on the line.

Received a call from this number didn't leave a msg(blank msg) 477k. Eats plan minutes.

called a couple of times in last 2-3 days. no one on the other side of the line

called at 1:08 AM EST.  Left no message.  Just woke the household.

this number called at 11:30 cst----left no message    on 12/31/09

Called at 11;20 pm CST on New Year's Eve.  No one spoke.  Line eventually disconnected.  Unable to reverse trace the call.on the internet.

just got a call from this number and no answer. must be a telemarketing company..amazing they would call on xmas eve.

called and when I answered no one was on the other end. What's up with this? Anyone have a clue? I've heard that some of these calls are just to see if anyone picks up so marketers know approximately when someone is home.

called my cell phone 6:36 AM on a Sunday. vm showed message, but none was left. no caller ID, just the number.

Called at 11:09pm ... no msg, or caller id except for number!

Called twice and went to voicemail. No message was left.  I called back with caller ID blocked and got a voicemail from an unidentified computer voice