Who I have the same questioned this topic

I have had calls from outside the USA  (011 502 575 79211) and would like to know how to stop or block them?   I have tried 'live chat' with Verizon asking for their help but it appears that no one is ever there to help.  Therefore, Is there a way I can stop and/or block these incoming calls from another country (I do not know anyone outside of the USA or is traveling) as I just might answer the call and be hit with a large bill?  Thank you.