Who was it that said, "if you can't identify at least 3 new problems introduced by any solution, you don't understand the situation?" Or you don't understand ours. After all, it's currently all getting done already this way. The question is of specific versus general cases. Not seeing the drawbacks because you can cite a place where something is successful does not solve the problem for everyone else.
I don't find a solution that requires customers to place phone calls to have some number changed somewhere acceptable either. Therefore it doesn't really apply. Just like DHCP won't work for dialup users (yeah, let's all configure L2TP tunnels over dialup and run DHCP over that! It'd suck, same point, different reasoning, not an applicable solution either.) (On a tangent about having to make phone calls after hardware changes, I was pretty surprised when a friend had to do that after she had received a replacement mobile phone after her previous had been stolen. In Europe, you get a new SIM card from the telco and a new phone from your insurance company, no additional trickery is needed.)
In reality, this is not a technical problem, hence there is no way to win.
Wisely spoken. Regards, -- Niels.