called me today; no message

This number called me one morning, and I didn't answer because I don't answer unknown numbers. They must have had me on re-dial because they mmediately called me again. I then ignored the call. They called again, and again, and again, and again... I kept ignoring the calls until it was up to 16 missed calls, one after another. I then turned my phone off. It was kinda scary. I called it back later and it didn't ring, it just went straight to an automated message that says "please try your call again later"

Also received call from this number. But it shows up as 11-571-448-0028.  Maybe it originated from outside of the US? Probably a spam as I don't know anyone with this number.

i RECIEVE  THREE CALLS A WEEK FROM THIS NUMBER. WHEN I ANSWER THERE IS NO RESPONSE FROM THE CALLER. HOW CAN I STOP THESE CALLS?