I have found that if you let it go to voicemail they realize it is a good number. Then they continue to call with different numbers continuously. If I don't recognize a number I ignore it and don't let it go to voicemail. You may miss some calls but you don't want to get inundated with phony calls.
As a consumer my self, I can understand the nuisance of receiving unwanted calls, and even worst leaving a Voice Mail. Verizon Wireless offers you different options to stop these calls and text messages. Please take a moment to review the link below: