You realize the flaws in this comment, right?
What if you had said that about making a success touch screen mobile OS using only one's fingers? Or a about creating a financially successful portable media player?
It's only not feasible until it is.
the reason why cell phones work is carriers own the frequencies. with the unlicensed spectrum anyone can transmit on those frequencies with the maximum power allowed by the FCC.
an iphone using unlicensed frequencies for everything would have to cope with a lot of interference from every microwave, wifi access point, other iphone and any other unlicensed device
and that's before you build out tens of thousands of towers with an internet connection to every single one