Who called from 2133333221

They have been calling my cell phone every day now for a week and when they hear my voice they hang up.  Maybe they are expecting to hear an elderly voice on the phone and keep calling back hoping they will answer.  Phones have blocking for individual phone numbers or most do, that is what I did.

i'm busy right now.. I will call you later.

Received a call from 2133333221.  Did not answer.  Caller ID said name was "2133333221".

Me too. This thread looks very old, but I won't answer.  If they can't leave a message, I can't answer :-P

I keep getting calls from this number, don't know who they are or what they want.