I have an I Phone 4 and I can block any calls. There is an "I" with a circle around it next to the incoming call number. Hit that and go all the way to the bottom and mark "Block This Caller". I don't know how other phones work but I'm sure there is a way. Good luck.
Could it be that you are not getting Verizon recording when you call back. It could be the scammers have that as a voice mail recording to throw you off the track. Just a thought.
Yet another scammer calling and we do not answer numbers from unknown callers or from calls out of state. Arkansas really? NO THANKS! We will not answer but will add your number to call block. Judgement will come to all people that use the phone and try and cheat people with their scams. You can't hide from God. No, not ever.