He is making it so. But that is interesting. The 80's system creators, probably let the authentication (rate and money counting) on the backend. And didn't fil

He is making it so. But that is interesting. The 80's system creators, probably let the authentication (rate and money counting) on the backend. And didn't filtered input probably because they thought anyone willing the cheat would just cut the wires and bypass any filter on the phone to send the tones... so in the end, the whole system was based on the tones being secret. The 90's system assumes anyone cheating would be deterred by the sofware on the phone, and leaves an open line? So it is based on everyone using the phone? what happens if someone bypass the phone and go to the wire directly? is there a tone?