I've asked before if anyone had experience with this particular board in relation to overvoltage, but now I'm just seeing ridiculously inconsistent results and curious if anyone has been able to work with this board. Using AdaFruit's libraries (with modification), just getting the # of SMS messages over and over yields some successes and some errors. At this point, if I just let it go for 5 minutes querying for SMS messages every couple seconds I'll probably get 80% failure and 20% success.
It takes 5V, so I'm using a (12V) car battery, buck converter to step it down, but obviously have plenty of power... maybe I need a capacitor for the sim808 to spike. This is incredibly frustrating and seemingly non-deterministic. I want to use this board because it's cheap and has a small form factor.
Board:
http://www.and-global.com/index.php/product/SIM808%20Breakout.html
My other post about this board:
https://forum.arduino.cc/index.php?topic=641410.0
Edit - solution
It turns out the *&^#$ breadboard was unable to carry the current. I had a small car battery wired to jumper wires, plugged into the breadboard +/- lines and had my buck converter plugged into the other end of the +/- line. Once I connected the wires directly to each other it's closer to 95% consistent. Not perfect but much better.