at what radius can you send peer-to-peer text messages / SMS over "ham radio"? suppose we have lots of people concentrated in a small area, like a college campus. Maybe a mile or so in diameter. We would like to set up a packet switched peer-to-peer SMS transmission using low cost long wave radio devices, without having a central "cell phone tower". I guess kind of like bluetooth P2P network, except over a more meaningful distance. What would be the complexity factors to consider in such a system, both technical and regulatory? What would be the likely maximum radius of the covered area? Could this work with radius of .5 mile? 1 mile? 200 meters perhaps? Is that radius also related to the typical radius of operation of modern police / dispatcher radios or is it an entirely separate issue because of the lack of the central "tower" antenna? Would the radio devices in such P2P configuration expend significantly more energy than the cell phone with tower setup? In terms of regulation, what is the typical transmission radius when personal radios stop being "toy" and start being government regulated?