Who called from 2124006325

I got a call from the same number on the same day.  They called about 3 times back-to-back and never left a message.  My phone service picked it up but they just kept say "hello".

Keeps calling doesn't say anything very annoying

This number calls at least once a day.  I am on the do not call list, but they don't care.

Keeps calling doesn't say anything very annoying; calls at least once a day.   Called back to see what answers but get a message that it cannot connect. ???

IMy Answering Machine Picked up, Caller Said Hello, Hello No Message...