Following a related conversation earlier, here's info on a DIY cellphone:

I'd love to follow any development that happens around here. Not a coder, but happy to test!

How Hard Is It to 'De-Anonymize' Cellphone Data?
http://j.mp/14oUhaC  (Science Daily)

  "The proliferation of sensor-studded cellphones could lead to a wealth
   of data with socially useful applications -- in urban planning,
   epidemiology, operations research and emergency preparedness, among
   other things. Of course, before being released to researchers, the
   data would have to be stripped of identifying information. But how
   hard could it be to protect the identity of one unnamed cellphone user
   in a data set of hundreds of thousands or even millions? According to
   a paper appearing this week in Scientific Reports, harder than you
   might think."