This is not Verizon's responsibility. They don't determine who can and cannot make a phone call to a number on their network.
Verizon has given you a method for doing what you would like to do. Whether or not you want to utilize it is up to you.
As sprmankalel has stated, if you don't recognize the number, don't answer. If it is important enough, they will leave a message. If the number is unknown or blocked, do the same.