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 ...

If you are looking for a compact GSM/GPRS module, you can get the SIM800L from most eBay traders. It is not the most judicious choice, but you can build your own basic GSM projects with a cheap modem ...