I can't see anything fundamentally wrong with it. A radio is a radio. I assume if you have access to what ever controls the cellular radio on the mobile device, you can pick and choose what frequency (out of the available ones like GSM, 3G, Etc.), send addressed packets over it, and talk to another modified device.
I was trying to research the subject. But I could only find people working with ad-hoc mesh networks over Wifi. Which to be honest, doesn't sound terribly useful considering Wifi's limited range of a few hundred feet at best. Whereas the cellular radio can talk over a few miles depending on conditions between it and the nearest tower.
I'm aware the FCC probably regulates that, but I'm excluding the legality part here. But if there is software out there I'm able to try out and it's iffy legally, I'll just do it inside a Faraday cage :P
So what are you guy's thoughts on this? Is the cellular radio something that's easy to control in say, Android devices? Is it something that'd require kernel modifications on most devices or could you possible do it through existing methods in the ROM? Do you think it'd be useful or practical if you had to operate without cell towers?
I suppose this is a question, but it's also discussion. I wasn't really sure whether or not to mark it as a question. Since I'm not really asking for someone's help since I'm likely not able to do this even if it's possible. More so I'm asking for opinions and thoughts on the idea since I'm interested in the thought. Though I'm sure it's been considered before, I haven't found anything that looks like it uses cellular radio in this way. Sorry if I shouldve marked this as a question.