Who called from 2012213968

I recieved a call from this number yesterday.  I tried to call it back today to see who it was but it just tells me my call can not go through.

Called this number back, and it was some customer service number. I just hung up.

Got two calls from this number today.  Upon calling it back I was given option to remove my number from call list.  I selected this option.  Needless to say within the hour I received another call.  This time i tried to speak to someone, but "due to large call volumes, there were no representatives available"

Got 4 missed calls in the last two days from 201-221-3968.
Checking with Verizon on how to get it blocked.

I received a call from this number at 5:00am CST, there was no one there when I answered. I called the number back and recieved a recording indicating the number was not in service.