How are telemarketers leaving voicemail messages without ringing the phone?

John says that there's a computer program called SlyDial which is able to bypass the ring of a phone and go directly to the voicemail, and it's likely that's what the telemarketers are using. It sends a tone that pushes right past the phone ring. At least the mystery is solved. We've also discovered that there's a voicemail box number which you can dial to bypass the phone. That has been around for years. Leo says that's voicemail spam any way you look at it, though.