I get these calls on my cell phone approximately once every day, the number seems to always be different, same call though. Usually they say nothing, I actually want them to say something so I can mess with them. They have called my work number in the past also.
I found this call very intresting in the fact that it was capable to call two diffrent cell phones and two diffrent cell providers at the same time. I was using verizon and my friend was using T-Mobile.