That's a really stupid thing about cell phones. We all carry these amazing radios with us, but they become completely useless once there is no tower around. Why can't phones be used as walkie-talkies?
Most cell phones already have Wifi, we would need a mesh (or at least special ad-hoc) standard for this and there you have your walkie talkie functionality with a bit of software.
There has been little success pushing one of those as apparently nobody cares about this feature.
If there were a way to whitelist authenticated phones of my friends, that could work.
And if you and your ilk load some kind of meshing or 'router app' on these advanced (non-hobbled) handheld radios, you might have a better chance of getting in touch with that out of range person by routing packets across radios until you're at the internet. Even if you limit the bandwidth to text messages for this feature, it could be a real lifesaver for folks needing to get emergency messages out.