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.

TK continues to explore the SIM800L GSM modem. ... (SIM800L) gets around 4.3 Vdc. Though most SIM800L modules work on 3.7 V, my SIM800L module from a new eBay seller seems to easily lose the network ...

Intro to the SIM800L. 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 ...