I did this project because I was annoyed with having to use my phone while driving to open the gate, which is GSM controlled by calling its number, and takes a while to open, so you really want to call in advance. This way I can just push two buttons.

It can also be used as a normal "phone"; it can make calls to any number, it has speaker and microphone, although both suck. I guess it's better than a smartphone with dead battery.

Theoretically, it can last 104 days in stand-by, with sleep consumption of ±1mA. But there are some problems with putting the display to sleep, so it sometimes draws a lot of current even when "off", so it's more like 3 days lol

Putting all the components in a small package sucks, with all the wires it's really hard to make it fit. It's held by tape now; it was designed to be glued, but I didn't want to do that yet. A better version should be on a custom PCB, just for the connections, I would keep the off-the-shelf boards. Maybe with a mosfet for the display.