Your idea is devilishly cool! I am not qualified to assess whether / how it could be implemented, but I wonder if it would be cost-efficient. Smartphones are no

Your idea is devilishly cool! I am not qualified to assess whether / how it could be implemented, but I wonder if it would be cost-efficient. Smartphones are not that cheap. A criminal organization would need some serious financial incentives to deploy such a network. In any case, it sounds really neat: an entirely distributed and decentralized. Such a system can't be brought down with a warrant. It can't be beheaded.