It rang once, then when I picked up to answer, they had already hung up.  It might  be someone spoof calling from overseas to get a dial tone,then phoning for free.  Or it might be a poll from any number of political campaigns.

I don't know how to block callers.

I have an IPhone and I did not have that happen

Hahaha, the DO NOT call list is a scam as well! DUH

I keep receiving calls from this number even after I have asked the to cease.

That spoof call thing is not the way you described and not hardly from a political campaign