Back in the day when ESS first came out and hacking local extenders would get a friendly visit from LE. I made what I called the "diverter box". I hooked it up at places like 7-11 and it worked well. If you want to see what 128v is like, just hook wires to the line, put the other ends of the wires in your mouth (be sure to strip away any shielding), then call the number. You'll be able to taste 128v.