Ring, Ring! Who's that callin'? It's your Arduino! Introducing Adafruit FONA 800 Shield, an adorable all-in-one cellular phone shield that lets you add voice, text, SMS and data to your project in an easy to use pluggable shield.This shield fits on top of any classic Arduino or compatible, and packs a surprising amount of technology into it's little frame. At the heart is a GSM cellular module (we use the latest SIM800) the size of a postage stamp. This module can do just about everything. If you want a...