SIM800L is a minuscule GSM module that offers 2G GSM/GPRS data ... one row contains all of the connections required to interface with a microcontroller like the venerable Arduino! To begin, you need ...

It is very easy to build an “SMS-controlled relay” with the help of a cheap GSM modem module and a small microcontroller board. Here, I’m using the SIM800L and Arduino Nano V3 ... delay(1000); ...

He decided to go with the low-cost SIM800L GSM modem, but as it only works on 2G networks, provisions have been made in the board design to swap it out for a more modern module should you desire.