EDIT: So in summary, this is not really possible, because of the scope of the software used to communicate with the antennae is to low level. It would be amazing, if this software was accessible to developers, as it would enable us to make more cool stuff. Unfortunately it isn't
I've had this idea ghosting around my mind for a while, but I don't know if it's possible. Could one develop a mesh network where phones used their internal radios to communicate with each other directly instead of first connecting to a tower? The idea being, that given proper software, cellular networks would no longer be needed. Basically: Imagine you want to use whatsapp but you don't have a data plan and you're out & about so consequently don't have wifi either. Can phone A connect to phone B (provided phone B has an internet connection) and piggyback off it's wifi?