There are 12 connections in total (6×2 rows) on the SIM800L module and, surprisingly, one row contains all of the connections required to interface with a microcontroller like the venerable Arduino!

Here, I’m using the SIM800L and Arduino Nano V3 to develop a nifty one-channel SMS relay. The device is, in fact, an “isolated electric switch” that can be controlled through the messaging app on your ...