The phone company, including cell phone provider, will block this number on request by you. You must be on the national do not call list & your state do not call list, if your state has one.
people calling from out of the country do not have to abide by US laws... I have gotten calls from them and asked them to stop calling and hung up on them, they immediately call right back!! I had a lady call me five times in a row once, I said stop calling this number each time... finally blew a whistle in her ear as loudly as possible and then blocked her number. I was completely dumbfounded at the way they targeted me, using the phone as a weapon. State attorney general says there is nothing they can do about this behavior and harassment.