Who called from 2130000000

I received calls sometime four to five times a day on my cell phone at wierd hours of the night.

I received 4 message on my VM from the number on 10/28, no message, just silence. No idea what this is...

anoying calls

recieved a 5 min message on voicemail with no one on the other line.

Irritating.... three calls from this phone # within the last half hour.  No one at the other end.