Vacuum tube cell-phone trivia from the latest Embedded Muse (http://www.ganssle.com/tem/tem306.html
A smart phone has well over 100 billion transistors. If we built one using tubes the phone would be about the size of 170 Vertical Assembly Buildings (the largest single-story building in the world). That would certainly discourage texting while driving. Weight? 2500 Nimitz-class aircraft carriers. And what a power hog! Figure over a terawatt, requiring all of the output of 500 of Olkiluoto power plants (the largest nuclear plant in the world). A tube-powered phone would run a cool $50 trillion, almost the GDP of the entire world.
And that's before AT&T's monthly data plan charges.