What if Verizon developed a system where a call is first greeted by a message that says to push button "1" (for example) to continue and "2" to leave a message. At that point Verizon will either go directly to Voicemail or continue with the call. The phone wouldn't ring until "1" is pressed. I'd also suggest giving the user the option to change the numbers so that the Robo callers don't put an automatic "1" in the call. This would also stop calls from call centers where there is a delay form their end to connect with the call. Just a suggestion.