You'll run into a variant of the tragedy of the commons; without any kind of regulation or provable assertions from people taking part in common communication infrastructure, it'd be quite easy to ruin it for everyone.
The problem right now is that even if I had a couple of million dollars lying around, I STILL couldn't reliably get a piece of hardware certified for the cellular network. I would have to set up a company, spend untold amounts of money bribing^Wwooing cellular company executives for a couple years, and, maybe, just maybe, I could get my phone through the certification process.
The technical aspects of certification are the easy part.
The problem is that the cellular companies fully understand that when it happens their power goes to zero because they suddenly become a dumb pipe that everybody just wants to ignore.
That's why this will take legislation.