215-874-2544 = Criminals. Robocall.

They did not leave a message so I did do not know who this is. I suspect that if they did not leave a message they are not important.
The call was from  Bristol, PA
I get his with so much of this crap when I register domains.

They have called a few more times and did not leave a message so they are blocked!

These are some idiots trying to do business loans, they called me 3 times just this morning and pissed me off.  Of course they are a bunch of Indians that are hired to annoy the crap out of people. How do I report them and block them?

You need to be signed up at donotcall.gov - the government has put in countless hours into thwarting spammers.   Many companies have been taken to court, so don't think nothing's being done, it's just that these parasites multiply like cockroaches.  At any rate, once signed up on the do not call registry, you can then report unwanted callers.  It's good that you actually spoke to them, so you have something to report.  Most people just don't answer their phones.  I always hope they leave a voice mail, so I can report in verbatim what was said.

Anyway, I hope that helps.