That sounds almost like the proposals to add a 1 cent cost to every e-mail sent in order to fix the spam problem. The main objection was that you would need to

That sounds almost like the proposals to add a 1 cent cost to every e-mail sent in order to fix the spam problem. The main objection was that you would need to get everyone to adopt the new system at the same time. But for IM, the system was already there and waiting.