Number 1 cell phone - : other components with polarity include the super-capacitor, the leds (note the two small green dots on one side), the atmega1284p microcontroller (note the circle in one corner), the m10 gsm module (which has an arrow in one corner), the sim card socket, the microphone, and the diode (note the faint grey line on one side). Sample response: " cpbs: "sm",50,250", with the "sm" indicating the sim card is the current phone book (some other options include "mc" for the missed call list, "rc" for the received call list, and "me" for the gsm module phone-book) and that 50 of its 250 entries are in use. Because of the ubiquity of cellphones, there are companies making the components they're made of; with some digging, i was able to find versions of these parts that are possible to buy in small quantities and that are possible to assemble by hand. Part of my motivation for making the phone -- and helping others to do the same -- is the fact that while cellphones are ubiquitous in our society, most of us have little idea what they're made of or how they work.
Kicking off 2017 with How to make a prop cell phone!