Hardware and software requirements

First, let's see what the required components for this project are. The most important parts are related to GSM functionalities, which is the central piece in our project. We'll need an antenna in order to be able to connect to the local GSM network. For this project, a flat uFL antenna is used:

Then, you'll need a way to actually use a SIM card, connect to the GSM network, and process the information with Arduino. There are many boards that can do this; however, I recommend the Adafruit FONA shield, which is very convenient to configure and use with Arduino. The following is the image of the Adafruit FONA shield along with the flat GSM antenna.

Then, you will need a battery to power the FONA shield, as the Arduino Uno board doesn't allow to power the chip that is at the core of the FONA shield (it can use up to 2A at a time!). For this, I used a 3.7 LiPo battery along with a micro USB battery charger:

A very important part of the project is the SIM card that...